Substrate processing apparatus, substrate processing method, substrate holding mechanism, and substrate holding method

ABSTRACT

An apparatus for processing a substrate is disclosed. The apparatus includes a polishing section configured to polish a substrate, a transfer mechanism configured to transfer the substrate, and a cleaning section configured to clean and dry the polished substrate. The cleaning section has plural cleaning lines for cleaning plural substrates. The plural cleaning lines have plural cleaning modules and plural transfer robots for transferring the substrates.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a substrate processing apparatus and asubstrate processing method, and more particularly to a substrateprocessing apparatus and a substrate processing method for use inpolishing a substrate, such as a semiconductor wafer, to provide aplanarized surface of the substrate.

The present invention also relates to a substrate holding mechanism anda substrate holding method, and more particularly to a substrate holdingmechanism suitable for use in a cleaning apparatus and a dryingapparatus for a substrate such as a semiconductor wafer.

The present invention also relates to units and several types ofcomponents and mechanisms for use in a substrate processing apparatus.

2. Description of the Related Art

The trend of a semiconductor device in recent years has been a highlyintegrated structure, which entails finer interconnects of a circuit anda smaller distance between the interconnects. In fabrication of thesemiconductor device, many kinds of materials are deposited in a shapeof film on a silicon wafer repeatedly to form a multilayer structure. Itis important for forming the multilayer structure to planarize a surfaceof a wafer. A polishing apparatus for performing chemical mechanicalpolishing (CMP) is typically used as one technique of planarizing thesurface of the wafer. This type of apparatus is often called a chemicalmechanical polishing apparatus.

This chemical mechanical polishing (CMP) apparatus typically includes apolishing table supporting a polishing pad thereon, a top ring forholding a wafer, and a nozzle for supplying a polishing liquid onto thepolishing pad. When polishing a wafer, the top ring presses the waferagainst the polishing pad, while the polishing liquid is supplied ontothe polishing pad. In this state, the top ring and the polishing tableare moved relative to each other, whereby the wafer is polished to havea planarized surface.

A substrate processing apparatus is an apparatus which has, in additionto the CMP apparatus, functions of cleaning the polished wafer anddrying the cleaned wafer. In this substrate processing apparatus, thereis a need to improve a throughput in substrate processing. Since thesubstrate processing apparatus has a variety of processing sectionsincluding a polishing section and a cleaning section, a processing delayin each processing section results in a decrease in the throughput ofthe substrate processing apparatus in its entirety. For example, in aconventional substrate processing apparatus, only a single cleaning lineis provided, while plural polishing units are provided. Consequently,plural polished wafers cannot be cleaned and dried simultaneously.Moreover, of plural processes on the cleaning line (e.g., a primarycleaning process, a secondary cleaning process, and a drying process),the slowest process becomes a rate-limiting step in all processes andthus decides a processing time (i.e., throughput) of all processes.

The throughput of the substrate processing apparatus in its entirety canbe affected not only by the processing sections, such as the polishingsection and the cleaning section, but also by a transfer mechanism fortransferring a wafer. Further, wafer transferring operations between thetop ring and the transfer mechanism can also affect the overallthroughput. In this manner, the throughput of the substrate processingapparatus as a whole depends on a variety of processing operations andtransferring operations.

For example, the substrate processing apparatus has a linear transporterfor transferring a wafer between polishing units. This lineartransporter moves the wafer linearly in a horizontal direction tothereby transfer the wafer to a wafer-transfer position in eachpolishing unit. Then, the wafer is pushed upward to the top ring by apusher which is provided separately from the linear transporter. In thismanner, since the horizontal movement and the vertical movement of thewafer are performed by the linear transporter and the pusher separately,a long time is needed in transferring the wafer.

The pusher is provided in the wafer-transfer position for each polishingunit. In addition, each pusher needs an XY stage for fine adjustment ofthe wafer-transfer position between the top ring and the pusher.Consequently, the wafer transfer mechanism has complicated structure asa whole and entails a lot of accompanying wires and pipes to beprovided. Moreover, if the transfer mechanism breaks down, it isnecessary to access the wafer-transfer position for repair, and this canmake it difficult to restore the transfer mechanism.

A long downtime of the substrate processing apparatus as a result of afailure and maintenance thereof leads to an increase in cost forprocessing a wafer. For this reason, easy maintenance has recently beenrequired for the substrate processing apparatus. It is also required toreduce components of the substrate processing apparatus to simplify thestructure thereof and to achieve a lower cost.

For example, the top ring swings between a polishing position above thepolishing pad and the wafer-transfer position. Accordingly, a swingingmechanism for the top ring requires a regular maintenance. This swingingmechanism includes bearings for supporting a swing shaft of the topring, a motor and reduction gears for driving the swing shaft. A topring head, which supports the top ring, is mounted on an upper end ofthe relatively long swing shaft, and the reduction gears and the motorare coupled to a lower end of the swing shaft. A bearing case isarranged around the bearings. This bearing case extends through apolisher pan which partitions a polishing room and a lower room belowthe polishing room. Further, the bearing case is located below thepolisher pan. A top ring assembly, including the top ring and the topring head, is relatively long and heavy. Therefore, the top ringassembly may present disadvantages in maintenance thereof.

In the conventional substrate processing apparatus, a pressure adjusterfor adjusting a pressing force of the top ring against a substrate isprovided outside the top ring head. This arrangement entails a longdistance between the pressure adjuster and the top ring and may cause adelay in an actual change in the pressing force in response to a commandfor changing the pressing force against the substrate.

Pure water is used for cleaning a top ring and a dresser provided ineach of the polishing units of the substrate processing apparatus. In aconventional structure, the pure water is supplied from a single headerto the polishing units through plural pipes. This structure may presenta problem that a flow rate of the pure water in one polishing unitbecomes unstable as a result of use of the pure water in the other.

In the fabrication processes of the semiconductor device, cleaning anddrying of a substrate (e.g., a semiconductor wafer) are performed aftera polishing process and a plating process. For example, in cleaning ofthe substrate, a substrate holding mechanism holds the substrate androtates the substrate. In this state, a cleaning liquid is supplied ontothe substrate. A mechanism having an actuator for driving chucks so asto hold the substrate is known as a conventional substrate holdingmechanism.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above drawbacks. Itis therefore a first object of the present invention to provide asubstrate processing apparatus, a component unit of the substrateprocessing apparatus, and a substrate processing method capable ofachieving a high throughput.

It is a second object of the present invention to provide a pure watersupply mechanism and pure water supply method capable of supplying purewater stably to plural polishing units.

It is a third object of the present invention to provide a top ringassembly capable of responding promptly to a command for changing apressing force against a substrate.

It is a fourth object of the present invention to improve theconventional substrate holding mechanism and to provide a substrateholding mechanism and a substrate holding method capable of holding asubstrate with a simple structure.

One aspect of the present invention for achieving the above first objectis to provide an apparatus for processing a substrate. The apparatusincludes: a polishing section configured to polish a substrate; atransfer mechanism configured to transfer the substrate; and a cleaningsection configured to clean and dry the polished substrate. The cleaningsection has plural cleaning lines for cleaning plural substrates.

According to the present invention, even when plural substrates arecarried successively into the cleaning section, these substrates can besorted into the plural cleaning lines as needed and can be cleaned inparallel. Further, because the substrates can be sorted into the pluralcleaning lines according to times required for cleaning and drying thesubstrates, a throughput of the overall process can be improved.Moreover, by equalizing processing times in the plural cleaning lines,the throughput of the overall process can be further improved.

In this specification, the term “cleaning line” means a route of asubstrate in the cleaning section when cleaned by plural cleaningmodules. The cleaning section according to the present invention hasadvantages that, while it has a function of cleaning a single substratesuccessively, it also has a function of cleaning plural substratessimultaneously.

In a preferred aspect of the present invention, the cleaning sectionincludes a sorting mechanism configured to sort the polished substratesinto the plural cleaning lines. With this configuration, the substrates(e.g., wafers) can be sorted according to the process times in theplural cleaning lines. Therefore, the process times of the pluralcleaning lines can be equalized.

In a preferred aspect of the present invention, the plural cleaninglines include plural primary cleaning modules for performing a primarycleaning operation on the substrate and plural secondary cleaningmodules for performing a secondary cleaning operation on the substrate.With this configuration, in the event of a failure of a cleaning module,it is possible to repair or replace the cleaning module without stoppingthe cleaning process of the substrate.

In a preferred aspect of the present invention, the plural primarycleaning modules are aligned along a vertical direction and the pluralsecondary cleaning modules are aligned along a vertical direction. Withthis configuration, a footprint (i.e., an installation area of theapparatus installed in a clean room or the like) can be small. In thiscase, it is possible to transfer a substrate between the plural primarycleaning modules or between the plural secondary cleaning modules.

In a preferred aspect of the present invention, the cleaning sectionincludes a first transfer robot which can access the plural primarycleaning modules and the plural secondary cleaning modules, and a secondtransfer robot which can access the plural secondary cleaning modules.With this configuration, the substrate can be transferred promptly andsecurely by the two transfer robots.

In a preferred aspect of the present invention, the plural cleaninglines include a temporary base on which the substrate is placedtemporarily. With this configuration, a time of carrying the substratein and out the cleaning module can be adjusted. Further, the route ofthe substrate in the cleaning section can be changed flexibly.

In a preferred aspect of the present invention, the cleaning sectionincludes plural drying modules for drying the plural substrates cleanedby the plural cleaning lines. With this configuration, the substrate canbe extracted in a dried state from the substrate processing apparatus.Therefore, the dry-in-dry-out type substrate processing apparatus can beprovided.

In a preferred aspect of the present invention, the plural dryingmodules are aligned along a vertical direction. With this configuration,the footprint can be small.

Another aspect of the present invention is to provide a method ofprocessing a substrate. The method includes: polishing pluralsubstrates; transferring the polished substrates to plural cleaninglines; sorting the polished substrates into the plural cleaning lines;cleaning the polished substrates in the plural cleaning lines; anddrying the cleaned substrates. According to the present invention, evenwhen plural substrates are carried successively into a cleaning section,these substrates can be sorted into the plural cleaning lines as neededand can be cleaned in parallel. Further, because the substrates can besorted into the plural cleaning lines according to times required forcleaning and drying the substrates, a throughput of the overall processcan be improved. Moreover, by equalizing processing times in the pluralcleaning lines, the throughput of the overall process can be furtherimproved.

In a preferred aspect of the present invention, the cleaning of thepolished substrates comprises cleaning the polished substrates inparallel in the plural cleaning lines. Since the substrates are cleanedin parallel, the cleaning time for these plural substrates can beshortened.

In a preferred aspect of the present invention, the cleaning of thepolished substrates comprises cleaning the polished substrates atpredetermined time intervals in the plural cleaning lines. Since theplural substrates are cleaned at the predetermined time intervals, evenwhen the cleaned substrates are needed to be transferred one by one, thetransfer robot can carry out the cleaned substrates successively atcertain time intervals. Therefore, the transferring operation does notbecome a rate-limiting step, and the throughput of the overall processcan be improved.

Another aspect of the present invention is to provide an apparatus forprocessing a substrate. The apparatus includes: a polishing sectionconfigured to polish a substrate using a top ring configured to apply apressing force to the substrate by pressure of a fluid; a transfermechanism configured to transfer the substrate; a cleaning sectionconfigured to clean and dry the polished substrate; and a pressureadjuster for adjusting the pressure of the fluid. The top ring isswingably coupled to a support shaft via a top ring head, and thepressure adjuster is provided on the top ring head.

The present invention can solve the following conventional drawbacks. Ina conventional substrate processing apparatus, a single pressureadjuster for plural polishing units is provided outside the top ringhead. Consequently, if one of the plural polishing units breaks down,the operation of the pressure adjuster for adjusting pressures in all ofthe top rings should be stopped. According to the present invention,even in a case where plural polishing units are provided in thepolishing section, the pressure adjuster is provided for each top ringin each of the polishing units, and therefore the operation of thepolishing unit, which is not in trouble, can continue. Therefore, thedecrease in the throughput of the substrate process in its entirety canbe prevented. From a viewpoint of lightweight of the top ring head, itis preferable to realize downsizing of a rotating mechanism and aswinging mechanism for the top ring. In addition, it is preferable thatcomponents (e.g., a top ring housing) of the top ring head and the topring be made from a lightweight material, such as vinyl chloride resinor fluororesin.

Further, the present invention can improve a delay in response of thepressing force of the top ring, which has been a drawback in theconventional substrate processing apparatus. Specifically, in theconventional substrate processing apparatus, the pressure adjuster isprovided outside the top ring head, as described above. This arrangemententails a long distance between the pressure adjuster and the top ringand can cause a delay in an actual change in the pressing force inresponse to a command for changing the pressing force against thesubstrate. According to the present invention, because the pressureadjuster is provided on the top ring head, the distance between thepressure adjuster and the top ring is short, as compared with theconventional structure. Therefore, the response of the fluid pressurecan be improved, and the pressing force can be changed rapidly accordingto a raised portion and a recess portion of the surface of thesubstrate. As a result, the pressing force of the top ring against thesubstrate can be controlled appropriately and accurately.

In a preferred aspect of the present invention, the apparatus furtherincludes a swinging mechanism configured to swing the top ring aroundthe support shaft. The swinging mechanism is arranged on the top ringhead.

In a preferred aspect of the present invention, the top ring head isremovably coupled to the support shaft.

With this configuration, the maintenance can be easily conducted.Further, the maintenance of individual top ring head can be performedwithout stopping the overall substrate processing operations.

According to the above-described configuration, the pressure adjusterand the swinging mechanism are provided on the top ring head itself,which allows an easy access. Therefore, it is not necessary to removeother device units adjacent thereto when the maintenance of the pressureadjuster and the swinging mechanism is to be conducted. Further, the topring, the top ring head, the pressure adjuster, and the swingingmechanism can be provided as one module (unit). Therefore, replacementof components of the swinging mechanism, such a bearing, a motor, andreduction gears, can be conducted for each module. As a result, anapparatus downtime (i.e., a time when a device is not in operationduring the maintenance thereof) can be reduced. In the high-throughputsubstrate processing apparatus, a reduction in the apparatus downtimeleads to a decrease in cost for processing substrates. In this manner,the substrate processing apparatus according to the present inventioncan allow the maintenance of the devices as the components thereof whileallowing the continuous operation of the apparatus. For example, even ifmaintenance frequency increases as the operation time of the apparatusincreases, the substrate processing apparatus can be used continuously.In addition, thanks to easy replacement and restoration operations, thesubstrate processing apparatus with a long useful life can be provided.

Another aspect of the present invention is to provide an apparatus forprocessing a substrate. The apparatus includes: a polishing sectionhaving plural polishing units each configured to polish a substrate; atransfer mechanism configured to transfer the substrate between theplural polishing units; and a cleaning section configured to clean anddry the polished substrate. The transfer mechanism includes pluraltransfer stages arranged on two travel axes at different heights, pluralhorizontal drive mechanisms configured to move the plural transferstages along the two travel axes in horizontal directions, and pluralelevating mechanisms configured to move the plural transfer stagesindependently in vertical directions.

With this configuration, the substrate can be transferred in thehorizontal direction and the vertical direction simultaneously.Therefore, a time for transferring the substrate can be shortened.Further, a conventionally-required pusher can be omitted. Therefore, thestructure can be simple and the easy maintenance of the transfermechanism can be realized. As a result, the downtime of the substrateprocessing apparatus can be shortened. Hence, an improved maintenance ofthe substrate processing apparatus can be realized, and the throughputof the substrate processing apparatus can be improved.

In a preferred aspect of the present invention, the apparatus furtherincludes: a pass stage arranged on a travel axis at a height differingfrom the heights of the two travel axes; and a horizontal drivemechanism configured to move the pass stage along the travel axis in ahorizontal direction. With this configuration, plural substrates can bemoved simultaneously in the horizontal directions at different heights.Therefore, the throughput of the substrate processing apparatus can beimproved.

Another aspect of the present invention is to provide an apparatus forprocessing a substrate. The apparatus includes: a polishing sectionhaving a vertically-movable top ring configured to hold a substrate, thetop ring including a top ring body and a retainer ring which isvertically movable relative to the top ring body; a transfer mechanismhaving a vertically-movable transfer stage configured to transfer andreceive the substrate to and from the top ring; and a retainer ringstation arranged between the top ring and the transfer stage. Theretainer ring station includes plural push-up mechanisms configured topush the retainer ring upward.

Another aspect of the present invention is to provide a retainer ringstation on which a top ring is to be placed. The top ring has a top ringbody and a retainer ring which is vertically movable relative to the topring body. The retainer ring station includes plural push-up mechanismsconfigured to push the retainer ring upward.

Because the retainer ring of the top ring is pushed upward by theretainer ring station which is provided independently of the top ringand the transfer stage, the top ring and the transfer stage can movecloser to and away from each other substantially simultaneously withoutwaiting each other when the substrate is to be transferred between thetop ring and the transfer stage. Therefore, a time of transferring thesubstrate between the top ring and the transfer stage can be shortened.Further, releasing of the substrate from the top ring is not hindered bythe retainer ring, and therefore the substrate can be securely releasedfrom the top ring. In a case of providing plural polishing units, thesubstrates can be securely released from the top rings and times oftransferring the substrates to the transfer stages can be securelycontrolled. Therefore, the times of transferring the substrates betweenthe top rings and the transfer stages can be equalized. As a result, thethroughput of the substrate processing operations in their entirety canbe improved.

In a preferred aspect of the present invention, each of the pluralpush-up mechanisms includes a push-up pin arranged to be brought intocontact with the retainer ring and a spring configured to push thepush-up pin upward.

In a preferred aspect of the present invention, the retainer ringstation has a wear measuring device configured to measure an amount ofwear of the retainer ring while the plural push-up mechanisms arepushing the retainer ring upward.

In a preferred aspect of the present invention, the wear measuringdevice includes a contact member arranged to be brought into contactwith an lower surface of the retainer ring, a spring configured to pushthe contact member upward, a linear guide vertically movably supportingthe contact member, and a displacement measuring device configured tomeasure a displacement of the contact member. With this configuration,the wear of the retainer ring can be measured without lowering thethroughput of the substrate processing apparatus in its entirety.

Another aspect of the present invention is to provide a method ofprocessing a substrate. The method includes: moving a top ring to atransfer position; transferring a substrate to the transfer position bya transfer stage; lowering the top ring to bring a retainer ring of thetop ring into contact with push-up mechanisms to cause the push-upmechanisms to push the retainer ring upward; during the lowering of thetop ring, elevating the transfer stage; transferring the substrate fromthe transfer stage to the top ring; moving the substrate from thetransfer position to a polishing position; and polishing the substrate.

According to the present invention, the top ring and the transfer stagecan move closer to and away from each other substantially simultaneouslywithout waiting each other when the substrate is to be transferredbetween the top ring and the transfer stage. Therefore, a time oftransferring the substrate between the top ring and the transfer stagecan be shortened. Further, releasing of the substrate from the top ringis not hindered by the retainer ring, and therefore the substrate can besecurely released from the top ring. In a case of providing pluralpolishing units, the substrates can be securely released from the toprings and times of transferring the substrates to the transfer stagescan be securely controlled. Therefore, the times of transferring thesubstrates between the top rings and the transfer stages can beequalized. As a result, the throughput of the substrate processingoperations in their entirety can be improved.

Another aspect of the present invention is to provide an atomizer forcleaning a polishing surface of a polishing pad with a high-pressurefluid. The atomizer includes: an arm having an ejection hole for thefluid; reinforcing members provided on both sides of the arm; a fluidpassage in fluid communication with the ejection hole; and a swing shaftrotatably supporting the arm. The arm is capable of swinging between acleaning position where the polishing surface is cleaned and an idleposition where a maintenance operation is performed.

According to the present invention, the maintenance (e.g., replacementof the polishing pad) can be performed simply by moving the arm to theidle position. Therefore, it is not necessary to remove and attach theatomizer when the maintenance operation is performed. As a result, thethroughput of the apparatus can be improved.

One aspect of the present invention for achieving the above secondobject is to provide a mechanism for supplying pure water to pluralpolishing units. The mechanism includes: plural distribution controllersprovided respectively in the plural polishing units; and a pure watersupply pipe configured to provide fluid communication between a purewater supply source and the plural distribution controllers.

Another aspect of the present invention is to provide a method ofsupplying pure water to plural polishing units. The method includes:supplying pure water to plural distribution controllers providedrespectively in plural polishing units; and supplying the pure waterfrom the plural distribution controllers to points of use in the pluralpolishing units.

According to the present invention, because the flow rate of the purewater is controlled at each of the polishing units, use of the purewater in one polishing unit hardly affects use of the pure water in theother. Therefore, stable supply of the pure water can be realized. Inthis manner, the present invention can solve a conventional problem inwhich the flow rate of the pure water in one polishing unit becomesunstable as a result of use of the pure water in the other.

One aspect of the present invention for achieving the above third objectis to provide a top ring assembly including: a top ring configured toapply a pressing force to a substrate by pressure of a fluid; a top ringhead configured to support the top ring; and a pressure adjusterconfigured to adjust the pressure of the fluid. The pressure adjuster ismounted on the top ring head.

According to the present invention, because the pressure adjuster isprovided on the top ring head, the distance between the pressureadjuster and the top ring is short, as compared with the conventionalstructure. Therefore, the response of the fluid pressure can beimproved, and the pressing force can be changed rapidly according to araised portion and a recess portion of the surface of the substrate. Asa result, the pressing force of the top ring against the substrate canbe controlled appropriately and accurately.

One aspect of the present invention for achieving the above fourthobject is to provide a substrate holding mechanism including: a base;substrate-support members supported by the base and configured to bemovable in a vertical direction relative to the base; substrate-clampportions provided on upper ends of the substrate-support members,respectively; a drive mechanism configured to move the substrate-supportmembers in the vertical direction; and a pressing mechanism configuredto cause at least one of the substrate-clamp portions on at least one ofthe substrate-support members to press a substrate in conjunction with adownward movement of the substrate-support members and configured tocause the at least one of the substrate-clamp portions to move away fromthe substrate in conjunction with an upward movement of thesubstrate-support members.

In a preferred aspect of the present invention, the pressing mechanismcomprises a rotating mechanism configured to rotate the at lease one ofthe substrate-support members about its own axis in conjunction with theupward movement and the downward movement of the substrate-supportmembers.

In a preferred aspect of the present invention, the at least one ofsubstrate-clamp portions is a cylindrical clamp arranged eccentricallywith respect to the axis of the at least one of substrate-supportmembers.

In a preferred aspect of the present invention, the pressing mechanismincludes: a first magnet attached to one of the base and the at leastone of substrate-support members; and a second magnet attached to theother one of the base and the at least one of substrate-support members.The first magnet is arranged so as to be in close proximity to thesecond magnet when the substrate-support members are moved downward, andthe first magnet and the second magnet are arranged such that a magneticforce acting between the first magnet and the second magnet in closeproximity to each other causes the at least one of substrate-supportmembers to move in a direction such that the at least one ofsubstrate-clamp portions presses a periphery of the substrate.

In a preferred aspect of the present invention, a third magnet isfurther attached to the at least one of substrate-support members or thebase to which the second magnet is attached; and the first magnet isarranged so as to be in close proximity to one of the second magnet andthe third magnet when the substrate-support members are movedvertically.

In a preferred aspect of the present invention, when the first magnetand the second magnet come close to each other, the magnetic forceacting between the first magnet and the second magnet rotates the atleast one of substrate-support members about its own axis in a directionsuch that the at least one of substrate-clamp portions presses theperiphery of the substrate, and when the first magnet and the thirdmagnet come close to each other, a magnetic force acting between thefirst magnet and the third magnet rotates the at least one ofsubstrate-support members about its own axis in a direction such thatthe at least one of substrate-clamp portions moves away from theperiphery of the substrate.

In a preferred aspect of the present invention, the second magnet andthe third magnet are arranged away from each other in the verticaldirection.

In a preferred aspect of the present invention, the at least one ofsubstrate-support members has a groove extending along its axis, aprotrusion is provided on the base, and the protrusion roughly engagesthe groove.

In a preferred aspect of the present invention, the pressing mechanismincludes: a helical groove formed on the at least one ofsubstrate-support members; and a pin provided on the base. The pinroughly engages the helical groove.

In a preferred aspect of the present invention, the substrate-supportmembers comprise at least four substrate-support members, and two of theat least four substrate-support members, which face each other, aremoved in the vertical direction without rotation.

In a preferred aspect of the present invention, the substrate holdingmechanism further includes a mechanism configured to rotate the base andthe substrate-support members.

Another aspect of the present invention is to provide a substrateholding mechanism including: a base; substrate-support members supportedby the base; substrate-clamp portions and positioning portions providedon upper ends of the substrate-support members; and a rotating mechanismconfigured to rotate at least one of the substrate-support members aboutits own axis. The substrate-clamp portions are arranged eccentricallywith respect to axes of the substrate-support members, and each of thepositioning portions has a side surface curved along a circle locatedconcentrically with respect to an axis of each substrate-support member.

Another aspect of the present invention is to provide a substrateholding method including: placing a substrate onto pluralsubstrate-support members; performing a holding process of holding thesubstrate by lowering the plural substrate-support members to causesubstrate-clamp portions on upper ends of the plural substrate-supportmembers to press the substrate; and performing a releasing process ofreleasing the substrate by elevating the plural substrate-supportmembers to cause the substrate-clamp portions to move away from thesubstrate.

In a preferred aspect of the present invention, the holding process isperformed by rotating at least one of the plural substrate-supportmembers so as to cause at least one of the substrate-clamp portions onthe at least one of the plural substrate-support members to press thesubstrate.

In a preferred aspect of the present invention, two of the pluralsubstrate-support members, which face each other, are moved in thevertical direction without rotation.

Another aspect of the present invention is to provide a method ofcleaning a substrate while holding the substrate. This method includes:performing a holding process of holding the substrate by pressing thesubstrate with substrate-clamp portions on upper ends of pluralsubstrate-support members covered with a spin cover; performing acleaning process of cleaning the substrate by supplying a cleaningliquid onto the substrate held by the substrate-clamp portions whilerotating the substrate; and performing a releasing process of releasingthe substrate by elevating the plural substrate-support members to causethe substrate-clamp portions to move away from the substrate. Theholding process and the releasing process are performed by verticalmovements of the plural substrate-support members.

Another aspect of the present invention is to provide a method of dryinga substrate while holding the substrate. This method includes:performing a holding process of holding the substrate by pressing thesubstrate with substrate-clamp portions on upper ends of pluralsubstrate-support members covered with a spin cover; performing a dryingprocess of drying the substrate by supplying a vapor, containingisopropyl alcohol, onto the substrate held by the substrate-clampportions while rotating the substrate; and performing a releasingprocess of releasing the substrate by elevating the pluralsubstrate-support members to cause the substrate-clamp portions to moveaway from the substrate. The holding process and the releasing processare performed by vertical movements of the plural substrate-supportmembers.

According to the above-described present invention, the throughput inthe substrate processing operations can be improved. In addition, thesubstrate processing apparatus which allows an easy maintenance thereofcan be realized, and units constituting such apparatus can be provided.

Further, according to the present invention, because the force ofholding the substrate is generated by the vertical movements of thesubstrate-support members, it is not necessary to provide an electricactuator. Therefore, the substrate holding mechanism with a simplestructure can be realized. The substrate holding mechanism according tothe present invention can be applied to a cleaning apparatus forcleaning a substrate by supplying a cleaning liquid onto the substratewhile rotating the substrate and a drying apparatus for dying asubstrate by rotating the substrate. Because the substrate holdingmechanism according to the present invention has a simple structure andis lightweight, a rotational load on the rotating assembly can bereduced, and therefore a long life of the substrate holding mechanismcan be realized. Furthermore, the substrate holding mechanism accordingto the present invention has an advantage that a small amount ofcleaning liquid is scattered around.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing a whole arrangement of a substrateprocessing apparatus according to an embodiment of the presentinvention;

FIG. 2 is a perspective view schematically showing a first polishingunit;

FIG. 3 is a schematic view showing a cross section of a top ring;

FIG. 4 is a cross-sectional view schematically showing another exampleof the top ring;

FIG. 5 is a cross-sectional view illustrating mechanisms for rotatingand swinging the top ring;

FIG. 6 is a cross-sectional view schematically showing an internalstructure of a polishing table;

FIG. 7 is a schematic view showing the polishing table having an opticalsensor;

FIG. 8 is a schematic view showing the polishing table having amicrowave sensor;

FIG. 9 is a perspective view showing a dresser;

FIG. 10 is a plan view showing a path of a movement of the dresser whendressing a polishing surface of a polishing pad;

FIG. 11A is a perspective view showing an atomizer;

FIG. 11B is a schematic view showing a lower portion of an arm of theatomizer;

FIG. 12A is a side view showing an internal structure of the atomizer;

FIG. 12B is a plan view showing the atomizer;

FIG. 13A is a perspective view showing a polishing liquid supply nozzle;

FIG. 13B is an enlarged schematic view showing a tip end of thepolishing liquid supply nozzle as viewed from below;

FIG. 14 is a schematic view showing pure-water supply pipes provided ina polishing section;

FIG. 15 is a perspective view schematically showing a first lineartransporter;

FIG. 16 is a schematic view illustrating vertical positions of atransfer stage of a first transfer hand, a transfer stage of a secondtransfer hand, a transfer stage of a third transfer hand, and a transferstage of a fourth transfer hand;

FIG. 17 is a schematic view illustrating vertical positions of transferstages of a second linear transporter;

FIG. 18 is a perspective view illustrating arrangements of retainer ringstations provided at a second transfer position, a third transferposition, a sixth transfer position, and a seventh transfer position,the transfer stages, and the top rings;

FIG. 19 is a perspective view showing the retainer ring station and thetransfer stage;

FIG. 20A is a side view showing a positional relationship between theretainer ring station and the top ring;

FIG. 20B is a plan view showing a positional relationship between theretainer ring station and the transfer stage;

FIG. 21 is a perspective view showing the retainer ring station on whichthe top ring is placed;

FIG. 22A is a cross-sectional view showing a push-up mechanism;

FIG. 22B is a cross-sectional view showing the push-up mechanism whencontacting the retainer ring;

FIG. 23 is a perspective view showing the retainer ring station with awear measuring device for measuring an amount of wear of the retainerring;

FIG. 24 is an enlarged cross-sectional view showing the wear measuringdevice shown in FIG. 23;

FIG. 25 is a side view showing the retainer ring station and the topring;

FIG. 26 is a perspective view showing a lifter;

FIG. 27 is a perspective view showing a swing transporter;

FIG. 28A is a plan view showing a cleaning section;

FIG. 28B is a side view showing the cleaning section;

FIG. 29 is a schematic view showing an example of a cleaning line;

FIG. 30 is a schematic view showing an example of the cleaning line;

FIG. 31 is a schematic view showing an example of the cleaning line;

FIG. 32 is a perspective view showing a primary cleaning module;

FIG. 33 is a vertical cross-sectional view showing a substrate holdingmechanism;

FIG. 34 is a plan view showing the substrate holding mechanism;

FIG. 35 is a vertical cross-sectional view showing the substrate holdingmechanism when a lifting mechanism is elevated;

FIG. 36A is a plan view showing part of a substrate-support member andan arm shown in FIG. 34;

FIG. 36B is a cross-sectional view taken along line A-A shown in FIG.34;

FIG. 36C is a cross-sectional view taken along line B-B shown in FIG.36B;

FIG. 37 is a schematic view showing an arrangement of a second magnetand a third magnet;

FIG. 38A is a plan view showing part of the substrate-support member andthe arm when the substrate-support member is elevated by the liftingmechanism;

FIG. 38B is a cross-sectional view taken along line A-A shown in FIG. 34when the substrate-support member is elevated by the lifting mechanism;

FIG. 38C is a cross-sectional view taken along line C-C shown in FIG.38B;

FIG. 39A is a side view showing the substrate-support member in a clampposition as viewed from a different angle;

FIG. 39B is a cross-sectional view taken along line D-D shown in FIG.39A;

FIG. 40A is a side view showing the substrate-support member in anunclamp position as viewed from a different angle;

FIG. 40B is a cross-sectional view taken along line E-E shown in FIG.40A;

FIG. 41A is an enlarged plan view showing a modified example of thesubstrate-support member and a clamp;

FIG. 41B is a side view showing the substrate-support member and theclamp shown in FIG. 41A;

FIG. 42A is a plan view showing a state in which a wafer is clamped;

FIG. 42B is a plan view showing a state in which the wafer is unclamped;

FIG. 43A is a cross-sectional view showing a modified example of part ofthe substrate holding mechanism;

FIG. 43B is a side view showing a substrate-support member shown in FIG.43A;

FIG. 44 is a vertical cross-sectional view showing an example in which aspin cover is attached to the substrate holding mechanism;

FIG. 45 is a vertical cross-sectional view showing an upper dryingmodule;

FIG. 46 is a plan view showing the upper drying module; and

FIG. 47 is an IPA supply unit for supplying an IPA vapor to a nozzle ofthe drying module.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described below withreference to the drawings. Identical or corresponding elements will bedenoted by identical reference numerals and repetitive descriptionsthereof will be omitted.

FIG. 1 is a plan view showing a whole arrangement of a substrateprocessing apparatus according to an embodiment of the presentinvention. As shown in FIG. 1, the substrate processing apparatus has ahousing 1 in a rectangular shape. An interior space of the housing 1 isdivided into a loading-unloading section 2, a polishing section 3, and acleaning section 4 by partitions 1 a and 1 b. The loading-unloadingsection 2, the polishing section 3, and the cleaning section 4 areassembled independently and each section is provided with an independentgas evacuation system. The substrate processing apparatus furtherincludes a controller 5 for controlling substrate processing operations.

The loading-unloading section 2 has two or more (four in thisembodiment) front loading units 20 on which wafer cassettes, eachstoring plural wafers (substrates), are placed. The front loading units20 are arranged adjacent to the housing 1 along a width direction of thesubstrate processing apparatus (a direction perpendicular to alongitudinal direction of the substrate processing apparatus). Each ofthe front loading units 20 is able to receive thereon an open cassette,an SMIF (Standard Manufacturing Interface) pod, or a FOUP (Front OpeningUnified Pod). The SMIF and FOUP are a hermetically sealed containerwhich houses a wafer cassette therein and covers it with a partition tothereby provide interior environments isolated from an external space.

The loading-unloading section 2 has a moving mechanism 21 extendingalong an arrangement direction of the front loading units 20. Twotransfer robots (loaders) 22 are installed on the moving mechanism 21and are movable along the arrangement direction of the front loadingunits 20. The transfer robots 22 are configured to move on the movingmechanism 21 so as to access the wafer cassettes mounted on the frontloading units 20. Each transfer robot 22 has vertically arranged twohands, which are separately used. For example, the upper hand can beused for returning a processed wafer to the wafer cassette, and thelower hand can be used for transferring a non-processed wafer. The lowerhand of the transfer robot 22 is configured to rotate about its ownaxis, so that it can reverse the wafer.

The loading-unloading section 2 is required to be a cleanest area.Therefore, pressure in the interior of the loading-unloading section 2is kept higher at all times than pressures in the exterior space of thesubstrate processing apparatus, the polishing section 3, and thecleaning section 4. On the other hand, the polishing section 3 is thedirtiest area, because slurry is used as a polishing liquid. Therefore,negative pressure is developed in the polishing section 3, and thepressure in polishing section 3 is kept lower than the internal pressureof the cleaning section 4. A filter fan unit (not shown in the drawings)having a clean air filter, such as HEPA filter or ULPA filter or achemical filter, is provided in the loading-unloading section 2. Thisfilter fan unit removes particles, toxic vapor, and toxic gas from airto form flow of clean air at all times.

The polishing section 3 is an area where a wafer is polished(planarized). This polishing section 3 includes a first polishing unit3A, a second polishing unit 3B, a third polishing unit 3C, and a fourthpolishing unit 3D. As shown in FIG. 1, the first polishing unit 3A, thesecond polishing unit 3B, the third polishing unit 3C, and the fourthpolishing unit 3D are arranged along the longitudinal direction of thesubstrate processing apparatus.

As shown in FIG. 1, the first polishing unit 3A includes a polishingtable 30A supporting a polishing pad 10 having a polishing surface, atop ring 31A for holding a wafer and pressing the wafer against thepolishing pad 10 on the polishing table 30A so as to polish the wafer, apolishing liquid supply nozzle 32A for supplying a polishing liquid anda dressing liquid (e.g., pure water) onto the polishing pad 10, adresser 33A for dressing the polishing surface of the polishing pad 10,and an atomizer 34A for ejecting a liquid (e.g., pure water) or amixture of a liquid (e.g., pure water) and a gas (e.g., nitrogen gas) inan atomized state onto the polishing surface of the polishing pad 10.

Similarly, the second polishing unit 3B includes a polishing table 30Bsupporting a polishing pad 10, a top ring 31B, a polishing liquid supplynozzle 32B, a dresser 33B, and an atomizer 34B. The third polishing unit3C includes a polishing table 30C supporting a polishing pad 10, a topring 31C, a polishing liquid supply nozzle 32C, a dresser 33C, and anatomizer 34C. The fourth polishing unit 3D includes a polishing table30D supporting a polishing pad 10, a top ring 31D, a polishing liquidsupply nozzle 32D, a dresser 33D, and an atomizer 34D.

The first polishing unit 3A, the second polishing unit 3B, the thirdpolishing unit 3C, and the fourth polishing unit 3D have the sameconfiguration. Therefore, the first polishing unit 3A will be describedbelow.

FIG. 2 is a perspective view schematically showing the first polishingunit 3A. The top ring 31A is supported by a top ring shaft 36. Thepolishing pad 10 is attached to an upper surface of the polishing table30A. An upper surface of the polishing pad 10 provides the polishingsurface where a wafer W is polished. Instead of the polishing pad 10, afixed abrasive may be used. The top ring 31A and the polishing table 30Aare configured to rotate about their own axes, as indicated by arrows.The wafer W is held on a lower surface of the top ring 31A via vacuumsuction. During polishing of the wafer W, the polishing liquid supplynozzle 32A supplies the polishing liquid onto the polishing surface ofthe polishing pad 10, and the top ring 31A presses the wafer W againstthe polishing surface to thereby polish the wafer W.

FIG. 3 is a schematic view showing a cross section of the top ring 31A.As shown in FIG. 3, the top ring 31A is coupled to a lower end of thetop ring shaft 36 via a universal joint 37. This universal joint 37 is aball joint configured to transmit rotation of the top ring shaft 36 tothe top ring 31A while allowing the top ring 31A and the top ring shaft36 to tile with respect to each other. The top ring 31A has a top ringbody 38 in substantially a disk shape and a retainer ring 40 provided ona lower portion of the top ring body 38. The top ring body 38 is made ofa material having high strength and rigidity, such as metal or ceramic.The retainer ring 40 is made of highly rigid resin, ceramic, or thelike. The retainer ring 40 may be formed integrally with the top ringbody 38.

The top ring body 38 and the retainer ring 40 form therein a space,which houses a circular elastic pad 42 arranged to be brought intocontact with the wafer W, an annular pressure sheet 43 made from anelastic membrane, and a substantially disk-shaped chucking plate 44holding the elastic pad 42. The elastic pad 42 has an upper peripheraledge, which is held by the chucking plate 44. Four pressure chambers(air bags) P1, P2, P3, and P4 are provided between the elastic pad 42and the chucking plate 44. A pressurized fluid (e.g., a pressurized air)is supplied into the pressure chambers P1, P2, P3, and P4 or a vacuum isdeveloped in the pressure chambers P1, P2, P3, and P4 via fluid passages51, 52, 53, and 54, respectively. The center pressure chamber P1 has acircular shape, and the other pressure chambers P2, P3, and P4 have anannular shape. These pressure chambers P1, P2, P3, and P4 are in aconcentric arrangement.

Internal pressures of the pressure chambers P1, P2, P3, and P4 can bechanged independently by a pressure adjuster (which will be describedlater) to thereby independently adjust pressing forces applied to fourzones: a central zone, an inner middle zone, an outer middle zone, and aperipheral zone. Further, by lowering the top ring 31A in its entirety,the retainer ring 40 can press the polishing pad 10 at a predeterminedpressing force. A pressure chamber P5 is formed between the chuckingplate 44 and the top ring body 38. A pressurized fluid is supplied intothe pressure chamber P5 or a vacuum is developed in the pressure chamberP5 via a fluid passage 55. With this configuration, the chucking plate44 and the elastic pad 42 in their entirety can be moved vertically.

The retainer ring 40 is arranged around the periphery of the wafer W soas to prevent the wafer W from coming off the top ring 31A duringpolishing of the wafer W. An opening (not shown in the drawing) isformed in a portion of the elastic pad 42 which forms the pressurechamber P3. When a vacuum is developed in the pressure chamber P3, thewafer W is hold by the top ring 31A via vacuum suction. On the otherhand, the wafer W is released from the top ring 31A by supplying anitrogen gas, dry air, pressurized air, or the like into the pressurechamber P3.

FIG. 4 is a cross-sectional view schematically showing another exampleof the top ring 31A. In this example, the chucking plate is notprovided. The elastic pad 42 is attached to a lower surface of the topring body 38. Further, the pressure chamber P5 is not provided betweenthe chucking plate and the top ring body 38. Instead, an elastic bag 46is provided between the retainer ring 40 and the top ring body 38, and apressure chamber P6 is formed in the elastic bag 46. The retainer ring40 is movable in the vertical direction relative to the top ring body38. A fluid passage 56 in fluid communication with the pressure chamberP6 is provided, so that the pressurized fluid (e.g., the pressurizedair) is supplied into the pressure chamber P6 through the fluid passage56. Internal pressure of the pressure chamber P6 is adjustable via thepressure adjuster, which will be described later. Therefore, thepressing force of the retainer ring 40 against the polishing pad 10 canbe adjusted independently of the pressing force applied to the wafer W.Other structures and operations are identical to those of the top ringshown in FIG. 3. The embodiment of the present invention can use eitherof top ring shown in FIG. 3 or FIG. 4.

FIG. 5 is a cross-sectional view illustrating mechanisms for rotatingand swinging the top ring 31A. The top ring shaft (e.g., spline shaft)36 is rotatably supported by a top ring head 60. The top ring shaft 36is coupled to a rotational shaft of a motor M1 via pulleys 61 and 62 anda belt 63. The top ring shaft 36 and the top ring 31A are rotated abouttheir own axes by the motor M1. This motor M1 is mounted on an upperportion of the top ring head 60. The top ring head 60 and the top ringshaft 36 are coupled to a pneumatic cylinder 65 as a vertical actuator.This pneumatic cylinder 65 is supplied with air (pressurized gas) tothereby move the top ring shaft 36 and the top ring 31A in unison in thevertical direction. Instead of the pneumatic cylinder 65, a mechanismhaving a ball screw and a servomotor may be used as the verticalactuator.

The top ring head 60 is rotatably supported by a support shaft 67 via abearing 72. This support shaft 67 is a fixed shaft and is madenon-rotatable. A motor M2 is mounted on the top ring head 60, andrelative position between the top ring head 60 and the motor M2 isfixed. The motor M2 has a rotational shaft, which is coupled to thesupport shaft 67 via a non-illustrated rotation transmission mechanism(e.g., gears). The rotation of the motor M2 causes the top ring head 60to pivot (swing) on the support shaft 67. The swinging motion of the topring head 60 causes the top ring 31A, supported by a tip end thereof, tomove between a polishing position above the polishing table 30A and atransfer position beside the polishing table 30A. In this embodiment,the motor M2 constitutes a swinging mechanism for swinging the top ring31A.

The top ring shaft 36 has a through-hole (not shown in the drawing)therein extending in a longitudinal direction thereof. Theabove-described fluid passages 51, 52, 53, 54, 55, and 56 of the topring 31A extend through this through-hole and are connected to a rotaryjoint 69 mounted on an upper end of the top ring shaft 36. Via therotary joint 69, the fluid, such as the pressurized gas (e.g., cleanair) or the nitrogen gas, is supplied to the top ring 31A and the gas isevacuated from the top ring 31A. Plural fluid pipes 70 are connected tothe rotary joint 69. These fluid pipes 70 are in fluid communicationwith the above-described fluid passages 51, 52, 53, 54, 55, and 56 (seeFIG. 3 and FIG. 4), and are coupled to a pressure adjuster 75. Fluidpipes 71 for supplying the pressurized air to the pneumatic cylinder 65are also coupled to the pressure adjuster 75.

The pressure adjuster 75 has electropneumatic regulators for regulatingthe pressure of the fluid to be supplied to the top ring 31A, pipescoupled to the fluid pipes 70 and 71, air-operated valves provided inthese pipes, electropneumatic regulators for regulating pressure of airserving as a working source for the air-operated valves, and ejectorsfor developing vacuum in the top ring 31A. These elements are integratedto form a single block (unit). The pressure adjuster 75 is secured tothe upper portion of the top ring head 60. The pressures of thepressurized gas to be supplied to the pressure chambers P1, P2, P3, P4,and P5 (see FIG. 3) and the pressure of the pressurized air to besupplied to the pneumatic cylinder 65 are regulated by theelectropneumatic regulators of the pressure adjuster 75. Similarly, thevacuum is developed in the air bags P1, P2, P3, and P4 of the top ring31A and in the pressure chamber P5 between the chucking plate 44 and thetop ring body 38 by the ejectors of the pressure adjuster 75.

Because the electropneumatic regulators and the valves, which arepressure-regulating devices, are arranged near the top ring 31A, thecontrollability of the pressures in the top ring 31A is improved. Morespecifically, because distances between the electropneumatic regulatorsand the pressure chambers P1, P2, P3, P4, and P5 are short, an improvedresponse to a pressure-changing command from the controller 5 can berealized. Similarly, because the ejectors, which are vacuum sources, arelocated near the top ring 31A, an improved response to a command fordeveloping the vacuum in the top ring 31A is realized. A back surface ofthe pressure adjuster 75 can be used as a seat for attachment ofelectrical devices. Therefore, it is possible to delete the need for aframe that has been conventionally required for attachments.

The top ring head 60, the top ring 31A, the pressure adjuster 75, thetop ring shaft 36, the motor M1, the motor M2, and the pneumaticcylinder 65 are provided as one module (which will be hereinafterreferred to as a top ring assembly 74). Specifically, the top ring shaft36, the motor M1, the motor M2, the pressure adjuster 75, and thepneumatic cylinder 65 are mounted on the top ring head 60. The top ringhead 60 is removably coupled to the support shaft 67. Therefore, byseparating the top ring head 60 from the support shaft 67, the top ringassembly 74 can be removed from the substrate processing apparatus. Thisconfiguration can provide easy maintenance of the support shaft 67, thetop ring head 60, and other components. For example, if the bearing 72makes an unusual sound, the bearing 72 can be easily replaced. Inaddition, replacement of the motor M2 and the rotation transmissionmechanism (e.g., reduction gears) can be conducted without removingadjacent components.

FIG. 6 is a cross-sectional view schematically showing an internalstructure of the polishing table 30A. As shown in FIG. 6, a sensor 76for detecting a state of a film of the wafer W is embedded in thepolishing table 30A. In this example, an eddy current sensor is used asthe sensor 76. An output signal of the sensor 76 is transmitted to thecontroller 5, which produces a monitoring signal indicating a thicknessof the film. Although a value of the monitoring signal (and the sensorsignal) does not indicate the film thickness itself, the value of themonitoring signal varies according to the film thickness. Therefore, themonitoring signal can be regarded as a signal indicating the filmthickness of the wafer W.

The controller 5 determines the internal pressures of the respectivepressure chambers P1, P2, P3, and P4 based on the monitoring signal, andcommands the pressure adjuster 75 to produce the determined pressures inthe respective pressure chambers P1, P2, P3, and P4. The controller 5functions as a pressure controller for operating the internal pressuresof the respective pressure chambers P1, P2, P3, and P4 based on themonitoring signal, and also functions as an end point detector fordetecting a polishing end point.

As with the first polishing unit 3A, sensors 76 are provided in thepolishing tables of the second polishing unit 3B, the third polishingunit 3C, and the fourth polishing unit 3D. The controller 5 producesmonitoring signals from output signals of the sensors 76 of thepolishing units 3A to 3D, and monitors progress of polishing of wafersin the polishing units 3A to 3D. When plural wafers are polished in thepolishing units 3A to 3D, the controller 5 monitors the monitoringsignals indicating film thicknesses of the wafers during polishing, andcontrols the pressing forces of the top ring 31A to 31D such that thepolishing times in the polishing units 3A to 3D become substantiallyequal. By adjusting the pressing forces of the top ring 31A to 31Dduring polishing based on the monitoring signals, the polishing times inthe polishing units 3A to 3D can be equalized.

The wafer W can be polished in any one of the first polishing unit 3A,the second polishing unit 3B, the third polishing unit 3C, and thefourth polishing unit 3D, or can be polished successively in the pluralpolishing units selected in advance from these polishing units 3A to 3D.For example, the wafer W can be polished in the first polishing unit 3Aand the second polishing unit 3B in this order, or can be polished inthe third polishing unit 3C and the fourth polishing unit 3D in thisorder. Further, the wafer W can be polished in the first polishing unit3A, the second polishing unit 3B, the third polishing unit 3C, and thefourth polishing unit 3D in this order. In any case, by equalizing theall polishing times in the polishing units 3A to 3D, the throughput canbe improved.

The eddy current sensor is preferably used in a case where the film ofthe wafer is a metal film. In a case where the film of the wafer is alight-transmissible film such as an oxide film, an optical sensor can beused as the sensor 76. Alternatively, a microwave sensor may be used asthe sensor 76. The microwave sensor can be used in both cases of a metalfilm and a non-metal film. Examples of the optical sensor and themicrowave sensor will be described below.

FIG. 7 is a schematic view showing the polishing table having an opticalsensor. As shown in FIG. 7, the optical sensor 76 for detecting a stateof a film of the wafer W is embedded in the polishing table 30A. Thissensor 76 is configured to emit light to the wafer W and detect thestate of the film (e.g., a thickness of the film) of the wafer W basedon intensity of the reflected light from the wafer W (i.e., based onreflection intensity or reflectance).

A light-transmissive member 77 for allowing light from the sensor 76 topass therethrough is provided in the polishing pad 10. Thelight-transmissive member 77 is made from a material having a hightransmittance, e.g., non-foamed polyurethane. Instead of providing sucha material having a high transmittance, a through-hole may be providedin the polishing pad 10. In this case, a transparent liquid is suppliedto the through-hole from below, while the through-hole is covered withthe wafer W, to form the light-transmissive member 77. Thelight-transmissive member 77 is arranged at a position such that itpasses through the center of the wafer W held by the top ring 31A.

As shown in FIG. 7, the sensor 76 has a light source 78 a, alight-emitting optical fiber 78 b as a light-emitting section fordirecting light from the light source 78 a to the surface of the waferW, a light-receiving optical fiber 78 c as a light-receiving section forreceiving reflected light from the surface of the wafer W, aspectroscope unit 78 d including a spectroscope for decomposing thelight, received by the light-receiving optical fiber 78 c, according towavelength and a plurality of light-receiving elements for storing thelight decomposed by the spectroscope as electric data, an operationcontroller 78 e for controlling timing of turning on and off the lightsource 78 a or starting to read the light-receiving elements in thespectroscope unit 78 d, and a power source 78 f for supplying electricpower to the operation controller 78 e. The light source 78 a and thespectroscope unit 78 d are supplied with electric power via theoperation controller 78 e.

A light-emitting end of the light-emitting optical fiber 78 b and alight-receiving end of the light-receiving optical fiber 78 c arearranged to be substantially perpendicular to the surface of the waferW. A photodiode array with 128 elements may be used as thelight-receiving elements in the spectroscope unit 78 d. The spectroscopeunit 78 d is coupled to the operation controller 78 e. Information fromthe light-receiving elements in the spectroscope unit 78 d istransmitted to the operation controller 78 e, where spectrum data of thereceived light is produced based on the information. Specifically, theoperation controller 78 e reads the electric information stored in thelight-receiving elements and generates the spectrum data of the receivedlight. This spectrum data indicates the intensity of the reflected lightdecomposed according to the wavelength, and varies depending on a filmthickness.

The operation controller 78 e is coupled to the above-describedcontroller 5. Thus, the spectrum data, generated by the operationcontroller 78 e, is transmitted to the controller 5. The controller 5calculates a characteristic value associated with the film thickness ofthe wafer W based on the spectrum data received from the operationcontroller 78 e, and uses the characteristic value as a monitoringsignal.

FIG. 8 is a schematic view showing the polishing table having amicrowave sensor. As shown in FIG. 8, the sensor 76 includes an antenna80 a for applying a microwave to the surface of the wafer W, a sensorbody 80 b for supplying the microwave to the antenna 80 a, and awaveguide 81 coupling the antenna 80 a to the sensor body 80 b. Theantenna 80 a is arranged so as to face the center of the wafer W held bythe top ring 31A.

The sensor body 80 b has a microwave source 80 c for generating themicrowave and supplying the microwave to the antenna 80 a, a separator80 d for separating the microwave (incident wave) generated by themicrowave source 80 c and the microwave (reflected wave) reflected uponthe surface of the wafer W, and a detector 80 e for receiving thereflected wave separated by the separator 80 d and detecting anamplitude and a phase of the reflected wave. A directional coupler issuitably used as the separator 80 d.

The antenna 80 a is coupled to the separator 80 d via the waveguide 81.The microwave source 80 c is coupled to the separator 80 d. Themicrowave generated by the microwave source 80 c is supplied to theantenna 80 a via the separator 80 d and the waveguide 81. The microwaveis applied from the antenna 80 a to the wafer W. The microwave permeates(penetrates) the polishing pad 10 to reach the wafer W. The reflectedwave from the wafer W permeates the polishing pad 10 again and isreceived by the antenna 80 a.

The reflected wave is sent from the antenna 80 a through the waveguide81 to the separator 80 d, which separates the incident wave and thereflected wave. The reflected wave separated by the separator 80 d istransmitted to the detector 80 e. The detector 80 e detects theamplitude and the phase of the reflected wave. The amplitude of thereflected wave is detected as a value of electric power (dbm or W) orvoltage (V). The phase of the reflected wave is detected by a phasemeasuring device (not shown) integrated in the detector 80 e. Theamplitude and the phase of the reflected wave are transmitted to thecontroller 5, where a thickness of a metal film or non-metal film of thewafer W is analyzed based on the amplitude and the phase of thereflected wave. The analyzed value is monitored as a monitoring signalby the controller 5.

FIG. 9 is a perspective view showing the dresser 33A that can be used inthe embodiment of the present invention. As shown in FIG. 9, the dresser33A has a dresser arm 85, a dressing member 86 rotatably mounted on atip end of the dresser arm 85, a swing shaft 88 coupled to the other endof the dresser arm 85, and a motor 89 as a driving mechanism forswinging the dresser arm 85 on the swing shaft 88. The dressing member86 has a circular dressing surface to which hard abrasive grains arefixed. Examples of the hard abrasive grains include diamond particlesand ceramic particles. A non-illustrated motor is installed in thedresser arm 85, and the dressing member 86 is rotated by this motor. Theswing shaft 88 is coupled to a non-illustrated elevating mechanism,which moves the dresser arm 85 downward to thereby cause the dressingmember 86 to press the polishing surface of the polishing pad 10.

FIG. 10 is a plan view showing a path of the movement of the dresser 33Awhen dressing the polishing surface of the polishing pad 10. As shown inFIG. 10, the dresser arm 85 is longer than a radius of the polishing pad10, and the swing shaft 88 is located radially outwardly of thepolishing pad 10. When dressing the polishing surface of the polishingpad 10, the polishing pad 10 is rotated and the dressing member 86 isrotated by the motor. Then, the dresser arm 85 is lowered by theelevating mechanism to bring the dressing member 86 into sliding contactwith the rotating polishing surface of the polishing pad 10. In thisstate, the dresser arm 85 is swung by the motor 89. During dressing ofthe polishing pad 10, pure water is supplied as a dressing liquid ontothe polishing surface from the polishing liquid supply nozzle 32A. Theswinging movement of the dresser arm 85 allows the dressing member 86 tomove across the polishing surface of the polishing pad 10 from one endto another via a center of the polishing surface, as shown in FIG. 10.This swinging movement of the dresser arm 85 enables the dressing member86 to dress the polishing surface of the polishing pad 10 in itsentirety including the center thereof and can greatly increase adressing effect on the polishing surface. Therefore, the polishingsurface can be dressed uniformly in its entirety, and a planar polishingsurface can be obtained.

After the dressing operation, the dresser arm 85 is moved to an idleposition A1 beside the polishing table 30A, as shown in FIG. 10. Whenthe maintenance of the dresser 33A is to be performed, the dresser arm85 is moved to a maintenance position A4 at substantially an oppositeside of the idle position A1. As shown in FIG. 10, during dressing, thedresser arm 85 may be swung between a position A2 at the edge of thepolishing surface and a position A3 at the center of the polishingsurface. This swinging motion can enable a rapid dressing operation andcan securely terminate the dressing operation.

In the above-described example, the dresser arm 85 and the dressingmember 86 are vertically moved in unison by the elevating mechanismcoupled to the swing shaft 88. This elevating mechanism may be disposedin the dresser arm 85, and the dressing member 86 may be movedvertically by this elevating mechanism disposed in the dresser arm 85.Further, in another modified example, a first elevating mechanism forvertically moving the swing shaft 88 may be provided, and a secondelevating mechanism for vertically moving the dressing member 86 may beprovided in the dresser arm 85. In this modified example, the firstelevating mechanism lowers the dresser arm 85 to a predetermined heightand then the second elevating mechanism lowers the dressing member 86.According to this configuration, a pressing force against the polishingsurface and a height of the dressing member 86 during the dressingoperation can be accurately adjusted.

FIG. 11A is a perspective view showing the atomizer 34A. The atomizer34A includes an arm 90 having one or more ejection holes on a lowerportion thereof, a fluid passage 91 coupled to the arm 90, and a swingshaft 94 supporting the arm 90. FIG. 11B is a schematic view showing thelower portion of the arm 90. In this example shown in FIG. 11B, pluralejection holes 90 a are formed at equal intervals on the lower portionof the arm 90. The fluid passage 91 may comprise a tube, or a pipe, or acombination of a tube and a pipe.

FIG. 12A is a side view showing an internal structure of the atomizer34A, and FIG. 12B is a plan view showing the atomizer 34A. The fluidpassage 91 has an open end, which is coupled to a fluid supply pipe (notshown in the drawing), so that a fluid is supplied to the fluid passage91 through the fluid supply pipe. Examples of the fluid to be usedinclude a liquid (e.g., pure water) and a mixture of a liquid and a gas(e.g., a mixture of pure water and a nitrogen gas). The fluid passage 91is in fluid communication with the ejection holes 90 a of the arm 90, sothat the fluid is atomized and ejected from the ejection holes 90 a ontothe polishing surface of the polishing pad 10.

The arm 90 is rotatable about the swing shaft 94 so as to swing betweena cleaning position and an idle position as indicated by a dotted linein FIG. 11A and FIG. 12B. The rotatable angle of the arm 90 is about 90degrees. Normally, the arm 90 is in the cleaning position and isarranged along the radial direction of the polishing surface of thepolishing pad 10, as shown in FIG. 1. When the maintenance (e.g.,replacement of the polishing pad 10) is to be performed, the arm 90 ismanually moved to the idle position. Therefore, it is not necessary toremove the arm 90 during maintenance, and the improved maintenance canbe realized. A rotating mechanism may be coupled to the swing shaft 94so as to swing the arm 90.

As shown in FIG. 12B, two reinforcing members 96 and 96, which havedifferent shapes, are provided on both sides of the arm 90. Thesereinforcing members 96 and 96 serve to prevent an axis of the arm 90from vibrating greatly when the arm 90 swings between the cleaningposition and the idle position. Therefore, an effective atomizingoperation can be performed. The atomizer 34A further includes a lever 95for fixing a swing position of the arm 90 (i.e., an angle range throughwhich the arm 90 can swing). Specifically, by operating the lever 95,the swingable angle of the arm 90 can be adjusted according toconditions. For example, when the lever 95 is rotated, the arm 90 canswing freely and can be moved manually between the cleaning position andthe idle position. On the other hand, when the lever 95 is tightened,the position of the arm 90 is fixed at either of the cleaning positionor the idle position.

The arm 90 of the atomizer may be a folding arm. Specifically, the arm90 may comprise at least two arm members coupled by a joint. In thisexample, an angle between the arm members when folded up is in a rangeof 1 degree to 45 degrees, preferably in a range of 5 degrees to 30degrees. If the angle between the arm members is larger than 45 degrees,the arm 90 occupies a large space. On the other hand, if the anglebetween the arm members is less than 1 degree, the arm 90 should have athin structure, which results in a low mechanical strength. In thisexample, the arm 90 may be configured not to rotate about the swingshaft 94. When the maintenance (e.g., replacement of the polishing pad10) is to be performed, the arm 90 can be folded up so as not to hinderthe maintenance operation. As another modified example, the arm 90 ofthe atomizer may be an extendable and contractible arm. In this casealso, when the maintenance is to be performed, the arm 90 can becontracted so as not to hinder the maintenance operation.

The purpose of providing the atomizer 34A is to wash away polishingdebris and abrasive grains remaining on the polishing surface of thepolishing pad 10 with the high-pressure fluid. Cleaning of the polishingsurface with the high-pressure fluid from the atomizer 34A andconditioning of the polishing surface by the mechanical contact of thedresser 33A can achieve a more preferable dressing, i.e., regenerationof the polishing surface. Typically, the regeneration of the polishingsurface is performed by the atomizer after the dressing operation isperformed by the contact-type dresser (e.g., diamond dresser).

FIG. 13A is a perspective view showing the polishing liquid supplynozzle 32A, and FIG. 13B is an enlarged schematic view showing a tip endof the polishing liquid supply nozzle 32A as viewed from below. As shownin FIG. 13A and FIG. 13B, the polishing liquid supply nozzle 32A hasmultiple tubes 100 through which pure water and the polishing liquid(e.g., slurry) are supplied onto the polishing surface of the polishingpad 10. The polishing liquid supply nozzle 32A further has a pipe arm101 covering the multiple tubes 100, and a swing shaft 102 supportingthe pipe arm 101. The multiple tubes 100 typically include a pure watersupply tube for supplying pure water and plural slurry supply tubes forsupplying different types of slurries. For example, the multiple tubes100 may comprise two to four (e.g., three) slurry supply tubes and oneor two pure water supply tubes.

The multiple tubes 100 extend through the pipe arm 101 to the tip end ofthe pipe arm 101. The pipe arm 101 covers substantially the entire tubes100. A reinforcing member 103 is secured to the tip end of the pipe arm101. Tip ends of the tubes 100 are located above the polishing pad 10,so that the polishing liquid is supplied from the tubes 100 onto thepolishing surface of the polishing pad 10. Arrow in FIG. 13A indicatesthe polishing liquid supplied onto the polishing surface. The swingshaft 102 is coupled to a non-illustrated rotating mechanism (e.g., amotor) for rotating the swing shaft 102. By rotating the swing shaft102, the polishing liquid can be supplied to a desired position on thepolishing surface. When the maintenance (e.g., replacement of thepolishing pad 10) is to be performed, the pipe arm 101 is swung on theswing arm 102 by the rotating mechanism to an idle position beside thepolishing table 30A.

As described above, because the multiple tubes 100 are coveredsubstantially in their entirety with the pipe arm 101, a surface area ofthe nozzle 32A in its entirety can be small, as compared with the casewhere the multiple tubes 100 are not covered with the pipe arm 101.Therefore, part of the slurry, scattered around during the polishingoperation or the cleaning operation by the atomizer, is attached to thesmall surface area. As a result, an adverse effect on the polishingprocess due to falling of the slurry attached is prevented. Further, itbecomes easy to clean the polishing liquid supply nozzle 32A.

FIG. 14 is a schematic view showing pure-water supply pipes provided inthe polishing section 3. In this substrate processing apparatus, thefirst polishing unit 3A and the second polishing unit 3B form a firstpolishing section 3 a as one unit, and the third polishing unit 3C andthe fourth polishing unit 3D form a second polishing section 3 b as oneunit. The first polishing section 3 a and the second polishing section 3b can be separated from each other. As described above, the polishingsection 3 uses several types of fluid, such as pure water, air, andnitrogen gas. For example, as shown in FIG. 14, the pure water (DIW,deionized water) is supplied from a pure-water supply source (not shownin the drawing) to a pure-water supply pipe 110 of the substrateprocessing apparatus. This pure-water supply pipe 110 extends throughthe polishing units 3A, 3B, 3C, and 3D of the polishing section 3, andis connected to distribution controllers 113 provided in the polishingunits 3A, 3B, 3C, and 3D, respectively.

The pure-water supply pipe 110 is divided between the first polishingsection 3 a and the second polishing section 3 b. The divided ends ofthe pure-water supply pipe 110 are coupled by a joint (not shown in thedrawing). Applications of the pure water to be used in each polishingunit include cleaning of the top ring (e.g., cleaning of acircumferential side surface of the top ring, cleaning of a substrateholding surface, cleaning of the retainer ring), cleaning of a transferhand for the wafer (e.g., cleaning of transfer hands of a first lineartransporter and a second linear transporter which will be describedlater), cleaning of a polished wafer, dressing of the polishing pad,cleaning of the dresser (e.g., cleaning of the dressing member),cleaning of the dresser arm, cleaning of the polishing liquid supplynozzle, and cleaning of the polishing pad by the atomizer.

The pure water flows through the pure-water supply pipe 110 into thedistribution controllers 113, and is distributed to points of use byeach distribution controller 113. The points of use are sites where thepure water is used (e.g., a nozzle for cleaning the top ring and anozzle for cleaning the dresser). The pure water is delivered from thedistribution controller 113 to terminal devices, such as the cleaningnozzles (e.g., the nozzle for cleaning the top ring and the nozzle forcleaning the dresser), provided in each polishing unit. For example, thepure water is supplied to the pure water supply tube 100 (see FIG. 13A)of the above-described polishing liquid supply nozzle at a flow rateregulated by the distribution controller 113 provided for each polishingunit. In this manner, because the distribution controller 113 isprovided for each polishing unit, the number of pipes to be installedcan be reduced, compared with a conventional structure in which the purewater is supplied from a single header to the polishing units throughplural pipes. Further, the arrangements with the reduced number of pipescan also reduce joints to be used to couple pipes between the firstpolishing section 3 a and the second polishing section 3 b. Therefore,the structure can be simple and a risk of leakage of the pure water isreduced. As shown in FIG. 14, it is preferable to provide a pure-watersupply pipe 112 dedicated for the atomizers, because the atomizers use alarge amount of pure water.

Each of the distribution controllers 113 has a valve box 113 a, amanometer (pressure measuring device) 113 b disposed upstream of thevalve box 113 a, and a flow-rate regulator 113 c disposed upstream ofthe manometer 113 b. The valve box 113 a is in fluid communication withthe points of use, such as the nozzle (not shown) for cleaning the topring and the pure water supply tube 100 (see FIG. 13A). Specifically,the valve box 113 a has plural pipes communicating with the points ofuse, and valves provided in these pipes.

The manometer 113 b is to measure pressure of the pure water to bedelivered to the valve box 113 a, and the flow-rate regulator 113 c isto adjust a flow rate of the pure water such that a measurement of themanometer 113 b is kept at a predetermined value. In this manner, sincethe flow rate of the pure water is controlled at each of the polishingunits, use of the pure water in one polishing unit hardly affects use ofthe pure water in the other. Therefore, stable supply of the pure watercan be realized. This embodiment can solve a conventional problem inwhich the flow rate of the pure water in one polishing unit becomesunstable as a result of use of the pure water in the other. In theexample shown in FIG. 14, the flow-rate regulators 113 c are providedfor all of the polishing units. Alternatively, one flow-rate regulator113 c may be provided for two polishing units. For example, a pair ofmanometer 113 b and flow-rate regulator 113 c may be provided upstreamof two valve boxes 113 b for the polishing units 3A and 3B, andsimilarly, a pair of manometer 113 b and flow-rate regulator 113 c maybe provided upstream of two valve boxes 113 b for the polishing units 3Cand 3D.

In the example shown in FIG. 14, the pure-water supply pipe 112dedicated for the atomizers 34A, 34B, 34C, and 34D is providedseparately from the pure-water supply pipe 110 that is provided for thepoints of use including the nozzle (not shown) for cleaning the top ringand the pure water supply tube 100. The pure-water supply pipe 112 iscoupled to the atomizers 34A, 34B, 34C, and 34D, and flow-ratecontrollers 114 are provided upstream of the atomizers 34A, 34B, 34C,and 34D, respectively. Each flow-rate controller 114 is configured toregulate a flow rate of the pure water supplied through the pure-watersupply pipe 112 and supply the pure water to the atomizer at theregulated flow rate.

As with the above-described distribution controller 113, each of theflow-rate controllers 114 includes a valve, a manometer, and a flow-rateregulator, which are arranged in the same manner as in the distributioncontroller 113. The controller 5 controls the operations of theflow-rate regulator of the flow-rate controller 114 based on themeasurement of the manometer of the flow-rate controller 114 such thatthe pure water is supplied to each atomizer at a predetermined flowrate.

As shown in FIG. 14, the pure-water supply pipe 110 and the pure-watersupply pipe 112 are coupled to the pure-water supply sourceindependently of each other to thereby establish independent pure-watersupply paths. This arrangement can prevent use of the pure water in theatomizers from affecting the flow rate of the pure water used in theother points of use.

While FIG. 14 illustrates the pure-water supply pipe 110 for supplyingthe pure water, the arrangements of the pipe and the distributioncontrollers as shown in FIG. 14 can be applied to supply pipes for otherfluid such as air, nitrogen gas, and slurry. For example, multipleslurry supply pipes for different types of slurries may be provided anddistribution controllers connected to the slurry supply pipes can beprovided for the respective polishing units. Each distributioncontroller delivers slurry, selected according to the polishing process,to the above-described polishing liquid supply nozzle (see FIG. 13A).Since the distribution controller is provided for each polishing unit,the type of slurry to be supplied to the polishing liquid supply nozzlecan differ between the polishing units. Further, the flow rate of theslurry to be supplied to the polishing liquid supply nozzle can beadjusted by the distribution controller.

Next, a transfer mechanism for transporting the wafer will be described.As shown in FIG. 1, a first linear transporter 6 is arranged adjacent tothe first polishing unit 3A and the second polishing unit 3B. This firstlinear transporter 6 is configured to transfer a wafer between fourtransfer positions located along an arrangement direction of thepolishing units 3A and 3B (hereinafter, these four transfer positionswill be referred to as a first transfer position TP1, a second transferposition TP2, a third transfer position TP3, and a fourth transferposition TP4 in the order from the loading and unloading section 2).

Further, a second linear transporter 7 is arranged adjacent to the thirdpolishing unit 3C and the fourth polishing unit 3D. This second lineartransporter 7 is configured to transfer a wafer between three transferpositions located along an arrangement direction of the polishing units3C and 3D (hereinafter, these three transfer positions will be referredto as a fifth transfer position TP5, a sixth transfer position TP6, anda seventh transfer position TP7 in the order from the loading andunloading section 2).

The wafer is transferred to the first polishing unit 3A and the secondpolishing unit 3B by the first linear transporter 6. As previouslydiscussed, the top ring 31A of the first polishing unit 3A is movedbetween the polishing position and the second transfer position TP2 bythe swinging motion of the top ring head 60. Therefore, the wafer istransferred to and from the top ring 31A at the second transfer positionTP2. Similarly, the top ring 31B of the second polishing unit 3B ismoved between the polishing position and the third transfer positionTP3, and the wafer is transferred to and from the top ring 31B at thethird transfer position TP3. The top ring 31C of the third polishingunit 3C is moved between the polishing position and the sixth transferposition TP6, and the wafer is transferred to and from the top ring 31Cat the sixth transfer position TP6. The top ring 31D of the fourthpolishing unit 3D is moved between the polishing position and theseventh transfer position TP7, and the wafer is transferred to and fromthe top ring 31D at the seventh transfer position TP7.

A lifter 11 is provided at the first transfer position TP1 for receivingthe wafer from the transfer robot 22. The wafer is transferred from thetransfer robot 22 to the first linear transporter 6 via the lifter 11. Ashutter (not shown in the drawing) is provided on the partition 1 a at aposition between the lifter 11 and the transfer robot 22. When the waferis to be transported, this shutter is opened to allow the transfer robot22 to deliver the wafer to the lifter 11. A swing transporter 12 isprovided between the first linear transporter 6, the second lineartransporter 7, and the cleaning section 4. This swing transporter 12 hasa hand that is movable between the fourth transfer position TP4 and thefifth transfer position TP5. Transferring of the wafer from the firstlinear transporter 6 to the second linear transporter 7 is performed bythe swing transporter 12. The wafer is transferred to the thirdpolishing unit 3C and/or the fourth polishing unit 3D by the secondlinear transporter 7. Further, the wafer, polished in the polishingsection 3, is transferred to the cleaning section 4 by the swingtransporter 12.

Next, structures of the first linear transporter 6, the second lineartransporter 7, the lifter 11, and the swing transporter 12 will bedescribed.

FIG. 15 is a perspective view schematically showing the first lineartransporter 6. The first linear transporter 6 includes first, second,third, and fourth transfer hands 121, 122, 123, and 124 having transferstages (substrate-transfer stages) 121 a, 122 a, 123 a, and 124 a onwhich a wafer is to be placed, three elevating mechanisms 130A, 130B,and 130C for vertically moving the second, third, and fourth transferhands 122, 123, and 124, three linear guides 132A, 132B, and 132Cconfigured to horizontally movably support the first, second, third, andfourth transfer hands 121, 122, 123, and 124, and three horizontal drivemechanisms 134A, 134B, and 134C for horizontally moving the first,second, third, and fourth transfer hands 121, 122, 123, and 124.Specific examples of the elevating mechanisms 130A, 130B, and 130Cinclude a pneumatic cylinder and a motor drive mechanism using a ballscrew. Each of the horizontal drive mechanisms 134A, 134B, and 134C hasa pair of pulleys 136, a belt 137 on these pulleys 136, and a servomotor138 for rotating one of the pulleys 136.

Plural pins are provided on an upper surface of each of the transferstages 121 a, 122 a, 123 a, and 124 a, and a wafer is placed onto thesepins. The transfer stages 121 a, 122 a, 123 a, and 124 a have sensors(not shown in the drawing) for detecting a wafer by using a transmissionsensor or the like. These sensors can detect whether a wafer is presenton the transfer stages 121 a, 122 a, 123 a, and 124 a.

The first transfer hand 121 is supported by the first linear guide 132A,and is moved between the first transfer position TP1 and the fourthtransfer position TP4 by the first horizontal drive mechanism 134A. Thisfirst transfer hand 121 is a pass hand for receiving a wafer from thelifter 11 and passing it to the second linear transporter 7. Therefore,the first transfer hand 121 is used in a case where a wafer is notpolished in the first polishing unit 3A and the second polishing unit3B, but is polished in the third polishing unit 3C and the fourthpolishing unit 3D. An elevating mechanism is not provided for the firsttransfer hand 121. Therefore, the transfer stage (i.e., a substrate passstage) 121 a of the first transfer hand 121 is movable only in thehorizontal direction.

The second transfer hand 122 is supported by the second linear guide132B, and is moved between the first transfer position TP1 and thesecond transfer position TP2 by the second horizontal drive mechanism134B. This second transfer hand 122 functions as an access hand fortransferring a wafer from the lifter 11 to the first polishing unit 3A.Specifically, the second transfer hand 122 is moved to the firsttransfer position TP1, where it receives the wafer from the lifter 11.Then, the second transfer hand 122 is moved to the second transferposition TP2 again, where it transfers the wafer on its transfer stage122 a to the top ring 31A. The first elevating mechanism 130A is coupledto the second transfer hand 122, and they are moved in unison in thehorizontal direction. When transferring the wafer on the transfer stage122 a to the top ring 31A, the second transfer hand 122 is elevated bythe first elevating mechanism 130A. After the wafer is transferred tothe top ring 31A, the second transfer hand 122 is lowered by the firstelevating mechanism 130A.

Plural (three in the drawing) access guides 140, which are shaped so asto engage a circumferential lower end of the top ring 31A (i.e., a lowerend of the retainer ring 40), are provided on the upper surface of thetransfer stage 122 a. Inner sides of the access guides 140 are taperedsurfaces. When the transfer stage 122 a is elevated to access the topring 31A, the top ring 31A is guided by the access guides 140, wherebythe top ring 31A engages the transfer stage 122 a. Upon this engagement,centering between the top ring 31A and the transfer stage 122 a (i.e.,the wafer) is performed. Access guides 140 are also provided on thetransfer stages 123 a and 124 a of the third and fourth transfer hands123 and 124, as well as the transfer stage 122 a.

The third transfer hand 123 and the fourth transfer hand 124 aresupported by the third linear guide 132C. The third transfer hand 123and the fourth transfer hand 124 are coupled to each other by apneumatic cylinder 142, so that the third transfer hand 123, the fourthtransfer hand 124, and the pneumatic cylinder 142 are moved in unison inthe horizontal direction by the third horizontal drive mechanism 134C.The pneumatic cylinder 142 functions as an interval adjuster foradjusting an interval between the transfer stage 123 a of the thirdtransfer hand 123 and the transfer stage 124 a of the fourth transferhand 124. The reason of providing the pneumatic cylinder (intervaladjuster) 142 is that an interval between the first transfer positionTP1 and the second transfer position TP2 may differ from an intervalbetween the second transfer position TP2 and the third transfer positionTP3. The pneumatic cylinder 142 can perform the interval adjustmentwhile the third transfer hand 123 and the fourth transfer hand 124 aremoving.

The third transfer hand 123 is coupled to the second elevating mechanism130B and the fourth transfer hand 124 is coupled to the third elevatingmechanism 130C, so that the third transfer hand 123 and the fourthtransfer hand 124 can be moved in the vertical directions independentlyof each other. The third transfer hand 123 is moved between the firsttransfer position TP1, the second transfer position TP2, and the thirdtransfer position TP3, and simultaneously the fourth transfer hand 124is moved between the second transfer position TP2, the third transferposition TP3, and the fourth transfer position TP4.

The third transfer hand 123 functions as an access hand for transferringa wafer from the lifter 11 to the second polishing unit 3B.Specifically, the third transfer hand 123 is moved to the first transferposition TP1, where it receives the wafer from the lifter 11. Then, thethird transfer hand 123 is moved to the third transfer position TP3,where it transfers the wafer on its transfer stage 123 a to the top ring31B. The third transfer hand 123 further functions as an access hand fortransferring a wafer polished in the first polishing unit 3A to thesecond polishing unit 3B. Specifically, the third transfer hand 123 ismoved to the second transfer position TP2, where it receives the waferfrom the top ring 31A. The third transfer hand 123 is further moved tothe third transfer position TP3, where it transfers the wafer on itstransfer stage 123 a to the top ring 31B. When transferring the waferbetween the transfer stage 123 a and the top ring 31A or top ring 31B,the third transfer hand 123 is elevated by the second elevatingmechanism 130B. After transferring of the wafer is completed, the thirdtransfer hand 123 is lowered by the second elevating mechanism 130B.

The fourth transfer hand 124 functions as an access hand fortransferring a wafer polished in the first polishing unit 3A or secondpolishing unit 3B to the swing transporter 12. Specifically, the fourthtransfer hand 124 is moved to the second transfer position TP2 or thirdtransfer position TP3, where it receives the polished wafer from the topring 31A or top ring 31B. Then, the fourth transfer hand 124 is moved tothe fourth transfer position TP4. When receiving the wafer from the topring 31A or top ring 31B, the fourth transfer hand 124 is elevated bythe third elevating mechanism 130C. After receiving the wafer, thefourth transfer hand 124 is lowered by the third elevating mechanism130C.

FIG. 16 is a schematic view illustrating vertical positions of thetransfer stage 121 a of the first transfer hand 121, the transfer stage122 a of the second transfer hand 122, the transfer stage 123 a of thethird transfer hand 123, and the transfer stage 124 a of the fourthtransfer hand 124. As shown in FIG. 16, the four transfer stages 121 ato 124 a are moved along three travel axes at different heights.Specifically, the transfer stage 121 a is moved along a first travelaxis at a lowest position, the transfer stage 123 a and the transferstage 124 a are moved along a third travel axis at a highest position,and the transfer stage 122 a is moved along a second travel axis locatedbetween the first travel axis and the third travel axis. Therefore, thetransfer stages 121 a, 122 a, 123 a, and 124 a can be moved horizontallywithout interfering with each other.

With this arrangement, the first linear transporter 6 can transfer awafer, received from the lifter 11, to either of the first polishingunit 3A or the second polishing unit 3B. For example, while a wafer istransferred to the first polishing unit 3A and polished in the firstpolishing unit 3A, a next wafer can be transferred directly to thesecond polishing unit 3B where the next wafer can be polished.Therefore, the throughput can be increased. In addition, it is possibleto transfer the wafer, polished in the first polishing unit 3A, to thesecond polishing unit 3B and further polish the wafer in the secondpolishing unit 3B. The second, third, and fourth transfer hands 122,123, and 124 can move in the vertical directions while moving in thehorizontal directions. For example, after receiving a wafer at the firsttransfer position TP1, the second transfer hand 122 can move upwardwhile it moves to the second transfer position TP2. Therefore, thesecond transfer hand 122 can promptly pass the wafer to the top ring 31Aright after the second transfer hand 122 reaches the second transferposition TP2. The third transfer hand 123 and the fourth transfer hand124 can perform such operations as well. Therefore, a time oftransferring a wafer can be reduced, and the throughput of the substrateprocessing apparatus can be improved. Moreover, because the transferstage 121 a of the first transfer hand 121 is located at the positionlower than other transfer hands, the transfer stage 121 a can transfer awafer to the fourth transfer position TP4 even when the other transferhand is accessing the top ring. In this manner, the arrangement of thethree travel axes can increase flexibility in transferring of the wafer.

The second linear transporter 7 has basically the same structures as thefirst linear transporter 6, but differs from the first lineartransporter 6 in that the second linear transporter 7 does not have anelement corresponding to the first transfer hand 121. FIG. 17 is aschematic view illustrating vertical positions of transfer stages of thesecond linear transporter 7. Structures of the second linear transporter7 that are identical to those of the first linear transporter 6 will notbe described repetitively. The second linear transporter 7 has a fifthtransfer hand 125, a sixth transfer hand 126, and a seventh transferhand 127. These fifth transfer hand 125, the sixth transfer hand 126,and the seventh transfer hand 127 have transfer stages 125 a, 126 a, and127 a, respectively, on which a wafer is to be placed.

The fifth transfer hand 125 and the sixth transfer hand 126 are coupledto each other by a pneumatic cylinder 142 as an interval adjuster, sothat the fifth transfer hand 125 and the sixth transfer hand 126 aremoved in unison in the horizontal direction. The transfer stage 125 aand the transfer stage 126 a are moved along a fifth travel axis, andthe transfer stage 127 a is moved along a fourth travel axis lower thanthe fifth travel axis. Therefore, the transfer stages 125 a, 126 a, and127 a can be moved horizontally without interfering with each other. Thefourth travel axis and the fifth travel axis are located at the sameheights of the second travel axis and the third travel axis of the firstlinear transporter 6.

The fifth transfer hand 125 is moved between the fifth transfer positionTP5 and the sixth transfer position TP6. This fifth transfer hand 125functions as an access hand for transferring a wafer to and receiving awafer from the top ring 31C. The sixth transfer hand 126 is movedbetween the sixth transfer position TP6 and the seventh transferposition TP7. This sixth transfer hand 126 functions as an access handfor receiving a wafer from the top ring 31C and transferring the waferto the top ring 31D. The seventh transfer hand 127 is moved between theseventh transfer position TP7 and the fifth transfer position TP5. Thisseventh transfer hand 127 functions as an access hand for receiving awafer from the top ring 31D and transferring the wafer to the fifthtransfer position TP5. Although not described, operations oftransferring of the wafer between the transfer hands 125, 126, and 127and the top rings 31C and 31D are identical to the above-describedoperations of the first linear transporter 6.

In the case where the top ring as shown in FIG. 4 is used as the toprings 31A to 31D, it is preferable to provide retainer ring stations,which will be describe below, at the second transfer position TP2, thethird transfer position TP3, the sixth transfer position TP6, and theseventh transfer position TP7, in order to facilitate or assist thewafer transferring operation between the top rings and the first andsecond linear transporters 6 and 7.

FIG. 18 is a perspective view illustrating arrangements of the retainerring stations provided at the second transfer position TP2, the thirdtransfer position TP3, the sixth transfer position TP6, and the seventhtransfer position TP7, the transfer stages, and the top rings. FIG. 19is a perspective view showing the retainer ring station provided at thesecond transfer position TP2 and the transfer stage. FIG. 20A is a sideview showing a positional relationship between the retainer ring stationand the top ring, and FIG. 20B is a plan view showing a positionalrelationship between the retainer ring station and the transfer stage.The retainer ring station provided at the second transfer position TP2will be described below.

The retainer ring station 143 includes plural push-up mechanisms 144configured to push the retainer ring 40 of the top ring 31A upward, anda support base 145 supporting these push-up mechanisms 144. The push-upmechanisms 144 are located at a vertical position between the top ring31A and the transfer stage (122 a or 123 a or 124 a) of the first lineartransporter 6. As shown in FIG. 20B, the push-up mechanisms 144 and thetransfer stage are arranged so as not to contact each other.

FIG. 21 is a perspective view showing the retainer ring station on whichthe top ring is placed. FIG. 22A is a cross-sectional view showing thepush-up mechanism 144, and FIG. 22B is a cross-sectional view showingthe push-up mechanism 144 when contacting the retainer ring. The push-upmechanism 144 includes a push-up pin 146 arranged to contact theretainer ring 40, a spring 147 as a biasing mechanism configured to pushthe push-up pin 146 upward, and a casing 148 configured to house thepush-up pin 146 and the spring 147 therein. The push-up mechanism 144 islocated such that the push-up pin 146 faces a lower surface of theretainer ring 40. When the top ring 31A is lowered, the lower surface ofthe retainer ring 40 is brought into contact with the push-up pins 146.The springs 147 have a pushing force that is large enough to push theretainer ring 40 upward. Therefore, as shown in FIG. 22B, the retainerring 40 is pushed upward by the push-up pins 146 to a position above thewafer W.

Next, operations of transferring a wafer from the first lineartransporter 6 to the top ring 31A will be described. First, the top ring31A is moved from the polishing position to the second transfer positionTP2. Then, the top ring 31A is lowered, and the retainer ring 40 islifted by the push-up mechanisms 144 of the retainer ring station 143,as described above. While the top ring 31A is lowered, the transferstage of the first linear transporter 6 is elevated to a position justbelow the top ring 31A without contacting the retainer ring 40. In thisstate, the wafer W is transferred from the transfer stage to the topring 31A. Then, the top ring 31A moves upward, and at substantially thesame time the transfer stage is lowered. The top ring 31A further movesto the polishing position, and then polishes the wafer W, while thetransfer stage starts its next transferring operation. The similaroperations are performed when the wafer is transferred from the top ring31A to the first linear transporter 6.

In this manner, when the wafer is transferred, the top ring 31A and thetransfer stage approach each other at substantially the same time, andmove away from each other at substantially the same time. Therefore, thethroughput can be improved. Retainer ring stations 143 provided at thethird transfer position TP3, the sixth transfer position TP6, and theseventh transfer position TP7 have the same structures as theabove-described retainer ring station 143, and the wafer transferringoperations are performed in the same manner.

During polishing of the wafer, the retainer ring 40 is placed in slidingcontact with the polishing surface of the polishing pad. As a result,the lower surface of the retainer ring 40 is worn away gradually. If thewear of the retainer ring 40 proceeds, the retainer ring 40 cannot holdthe wafer during polishing and the wafer can be spun off from therotating top ring 31A. To avoid this, it is necessary to replace theretainer ring 40 regularly. Conventionally, the replacement time of theretainer ring 40 is determined based on the number of wafers processed.However, this way of determining the replacement time is problematicbecause the retainer ring 40 is replaced even if it can be still used orthe wafer may be spun off from the top ring 31A as a result of excesswear of the retainer ring 40. In the following example, to avoid suchproblems, a wear measuring device for measuring an amount of wear(abrasion loss) of the retainer ring 40 is provided in the retainer ringstation 143.

FIG. 23 is a perspective view showing the retainer ring station 143 witha wear measuring device for measuring an amount of wear of the retainerring 40. FIG. 24 is an enlarged cross-sectional view showing the wearmeasuring device shown in FIG. 23. FIG. 25 is a side view showing theretainer ring station 143 and the top ring 31A. The wear measuringdevice 149 is mounted on the support base 145 which supports the push-upmechanisms 144. A relative position between the wear measuring device149 and the push-up mechanisms 144 is fixed. The wear measuring device149 includes, as shown in FIG. 24, a contact member 149 a arranged to bebrought into contact with the lower surface of the retainer ring 40, aspring 149 b configured to push the contact member 149 a upward, alinear guide 149 c configured to vertically movably support the contactmember 149 a, and a contact-type displacement sensor (displacementmeasuring device) 149 d configured to measure a displacement of thecontact member 149 a. A ball spline can be used as the linear guide 149c. Instead of the contact-type displacement sensor, non-contact-typedisplacement sensor (e.g., an optical displacement sensor) may be used.

The contact member 149 a has an L shape as viewed from a lateraldirection and has a lower end located at substantially the same heightas the push-up pins 146. When the top ring 31A is placed onto theretainer ring station 143, the lower end of the contact member 149 acontacts the lower surface of the retainer ring 40 at substantially thesame time the push-up pins 146 contacts the lower surface of theretainer ring 40. The displacement sensor 149 d is arranged above thecontact member 149 a. The contact member 149 a is biased upward by thespring 149 b and an upper end of the contact member 149 a is in contactwith the displacement sensor 149 d at all times. Therefore, a verticaldisplacement of the contact member 149 a is measured by the displacementsensor 149 d. The displacement sensor 149 d is coupled to the controller5, so that a measurement of the displacement sensor 149 d is sent to thecontroller 5.

When the top ring 31A is lowered and placed onto the retainer ringstation 143, the push-up pins 146 and the contact member 149 a contactthe lower surface of the retainer ring 40 of the top ring 31A. The topring 31A is further lowered until it stops at a predetermined height,and simultaneously the retainer ring 40 is pushed upward by the push-uppins 146. At this time, the contact member 149 a is pushed downward bythe retainer ring 40. The displacement of the contact member 149 a ismeasured by the displacement sensor 149 d, and the measurement istransmitted to the controller 5. While the displacement sensor 149 d ismeasuring the displacement of the contact member 149 a, the wafer istransferred between the top ring 31A and the transfer stage.

The displacement of the contact member 149 a, i.e., the measurement ofthe displacement sensor 149 d, varies according to the amount of wear ofthe retainer ring 40. More specifically, as the amount of wear of theretainer ring 40 increases, the measurement of the displacement sensor149 d decreases. A predetermined threshold, indicating the replacementtime of the retainer ring 40, is set in the controller 5. The controller5 determines the replacement time of the retainer ring 40 by detectingthat the measurement of the displacement sensor 149 d reaches the presetthreshold. It is preferable to provide the wear measuring device 149 notonly in the retainer ring station 143 provided at the second transferposition TP2, but also in the retainer ring stations provided at thethird transfer position TP3, the sixth transfer position TP6, and theseventh transfer position TP7.

According to this example, because the replacement time of the retainerring 40 is determined based on the amount of wear of the retainer ring40, replacement frequency of the retainer ring 40 can be reduced and thecost can be lowered. In addition, the wafer can be prevented from comingoff the top ring during polishing. Further, since the measuringoperation of the amount of wear of the retainer ring 40 is performedduring transferring of the wafer between the top ring 31A and thetransfer stage, the measuring operation does not lower the throughout ofthe substrate processing apparatus. Specifically, pushing the retainerring 40 upward by the push-up pins 146 and measuring the amount of wearof the retainer ring 40 by the wear measuring device 149 are necessarilyperformed at the same time. Accordingly, it is not necessary to providea time for measuring the amount of wear of the retainer ring 40. As aresult, the throughput of the apparatus as a whole can be improved.

FIG. 26 is a perspective view showing the lifter 11. The lifter 11 isarranged in a position such that the arm of the transfer robot 22 (seeFIG. 1) can access it. The lifter 11 includes a placement stage 150 onwhich the wafer is to be placed, a support shaft 151 supporting theplacement stage 150, and an elevating mechanism 152 configured to movethe placement stage 150 in the vertical direction. Specific examples ofthe elevating mechanism 152 include a pneumatic cylinder and a motordrive mechanism using a ball screw. The placement stage 150 is locatedat the first transfer position TP1. Four pins 153 are provided on anupper surface of the placement stage 150, so that the wafer W is placedonto these pins 153. The lower arm of the transfer robot 22 rotatesabout its own axis through 180 degrees to thereby reverse the wafer, andthen places the reversed wafer onto the placement stage 150 of thelifter 11. FIG. 26 shows the reversed wafer W. In this embodiment, thearm of the transfer robot 22 functions as a reversing device. Therefore,it is not necessary to provide the reversing device which wasnecessarily installed in a conventional apparatus. As a result, a stepof reversing the wafer W after the lifter receives the wafer W can beomitted. Therefore, the throughput in the overall processes can beincreased.

The transfer stage 122 a (or 121 a or 123 a) of the first lineartransporter 6 at the first transfer position TP1 and the placement stage150 of the lifter 11 are arranged along the same vertical axis. As shownin FIG. 26, when viewed from the vertical direction, the transfer stage122 a and the placement stage 150 are shaped so as not to overlap. Morespecifically, the transfer stage 122 a of the first linear transporter 6has a notch 155 shaped so as to allow the placement stage 150 to passtherethrough. This notch 155 is slightly larger than the placement stage150.

The lifter 11 receives the wafer W, reversed by the arm of the transferrobot 22, with the placement stage 150 located in the elevated position,and then the placement stage 150 is driven by the elevating mechanism152 to move downward. When the placement stage 150 passes through thetransfer stage 122 a of the first linear transporter 6, only the wafer Wis placed onto the transfer stage 122 a. The placement stage 150 isfurther lowered until it reaches a predetermined stop position. In thismanner, the wafer W is transferred from the lifter 11 to the firstlinear transporter 6. In this embodiment, the arm of the transfer robot22 functions as a reversing device. Therefore, it is not necessary toprovide the reversing device which was necessarily installed in aconventional apparatus. As a result, the number of operations fortransferring the wafer from the transfer robot 22 to the first lineartransporter 6 can be reduced, and errors in the wafer transferringoperations and the transferring time can be reduced.

The support shaft 151 of the lifter 11 has a reversed L shape, and has avertical portion located outwardly of the placement stage 150.Specifically, when viewed from the vertical direction, the placementstage 150 and the vertical portion of the support shaft 151 are arrangedso as not to overlap. Further, the support shaft 151 is located off thetravel path of the transfer stage of the first linear transporter 6.Therefore, the transfer stage of the first linear transporter 6 can moveto the first transfer position TP1 regardless of the vertical positionof the placement stage 150 of the lifter 11. Hence, the throughput canbe increased.

FIG. 27 is a perspective view showing the swing transporter 12. Theswing transporter 12 is mounted on a frame 160 of the substrateprocessing apparatus. The swing transporter 12 includes a linear guide161 extending in the vertical direction, a swinging mechanism 162mounted on the linear guide 161, and an elevating mechanism 165 as adrive source for moving the swinging mechanism 162 in the verticaldirection. A robo cylinder (electric actuator) having a servomotor and aball screw may be used as the elevating mechanism 165. A reversingmechanism 167 is coupled to the swinging mechanism 162 via a swing arm166. Further, a holding mechanism 170 for holding the wafer W is coupledto the reversing mechanism 167. A temporary base 180 for the wafer W isarranged beside the swing transporter 12. This temporary base 180 ismounted on a non-illustrated frame. As shown in FIG. 1, the temporarybase 180 is arranged adjacent to the first linear transporter 6 andlocated between the first linear transporter 6 and the cleaning section4.

The swing arm 166 is coupled to a motor (not shown in the drawing) ofthe swinging mechanism 162, so that when the motor is set in motion, theswing arm 166 pivots (swings) on a rotational shaft of this motor. Thisswinging motion of the swing arm 166 causes the reversing mechanism 167and the holding mechanism 170 to perform a swinging motion integrally,whereby the holding mechanism 170 is moved between the fourth transferposition TP4, the fifth transfer position TP5, and the temporary base180.

The holding mechanism 170 has a pair of holding arms 171 configured tohold the wafer W. Chucks 172 for holding a periphery of the wafer W areprovided on both ends of each holding arm 171. These chucks 172 areshaped so as to project downward from the both ends of the holding arm171. The holding mechanism 170 further has an opening-closing mechanism173 configured to move the pair of holding arms 171 closer to and awayfrom the wafer W.

When the wafer W is to be held, the holding arms 171 are opened and theholding mechanism 170 is lowered by the elevating mechanism 165 untilthe chucks 172 of the holding arms 171 lie in the same plane as thewafer W. Then, the holding arms 171 are moved closer to each other bythe opening-closing mechanism 173 to thereby hold the periphery of thewafer W with the chucks 172 of the holding arms 171. In this state, theholding arms 171 are elevated by the elevating mechanism 165.

The reversing mechanism 167 includes a rotational shaft 168 coupled tothe holding mechanism 170, and a motor (not shown in the drawing) forrotating the rotational shaft 168. The rotational shaft 168 is driven bythe motor to cause the holding mechanism 170 to rotate in its entiretythrough 180 degrees, thereby reversing the wafer W held by the holdingmechanism 170. In this manner, the holding mechanism 170 in its entiretyis reversed by the reversing mechanism 167. Therefore, a conventionallyrequired transferring operation between a holding mechanism and areversing mechanism can be omitted. When the wafer W is transferred fromthe fourth transfer position TP4 to the fifth transfer position TP5, thewafer W is not reversed by the reversing mechanism 167, and istransferred with its surface (i.e., the surface to be polished) facingdownward. On the other hand, when the wafer W is transferred from thefourth transfer position TP4 or the fifth transfer position TP5 to thetemporary base 180, the wafer W is reversed by the reversing mechanism167 such that a polished surface faces upward.

The temporary base 180 has a base plate 181, plural (two in FIG. 27)vertical rods 182 secured to an upper surface of the base plate 181, anda single horizontal rod 183 secured to the upper surface of the baseplate 181. The horizontal rod 183 has a reverse L-shape. This horizontalrod 183 has a vertical portion 183 a connected to the upper surface ofthe base plate 181 and a horizontal portion 183 b extending horizontallyfrom an upper end of the vertical portion 183 a toward the holdingmechanism 170. Plural (two in FIG. 27) pins 184 for supporting the waferW are provided on an upper surface of the horizontal portion 183 b.Similarly, pins 184 for supporting the wafer W are provided on upperends of the vertical rods 182, respectively. Tip ends of these pins 184lie in the same horizontal plane. The horizontal rod 183 and thevertical rods 182 are arranged such that a center of the swingingmovement of the wafer W (i.e., the rotational shaft of the motor of theswinging mechanism 162) is located nearer to the horizontal rod 183 thanthe vertical rods 182.

The holding mechanism 170, holding the wafer W reversed by the reversingmechanism 167, moves into a gap between the horizontal portion 183 b ofthe horizontal rod 183 and the base plate 181. When all of the pins 184are located below the wafer W, the swinging movement of the holdingmechanism 170 by the swinging mechanism 162 is stopped. In this state,the holding arms 171 are opened, whereby the wafer W is placed onto thetemporary base 180. The wafer W, placed on the temporary base 180, isthen transferred to the cleaning section 4 by a transfer robot of thecleaning section 4 which will be described below.

FIG. 28A is a plan view showing the cleaning section 4, and FIG. 28B isa side view showing the cleaning section 4. As shown in FIG. 28A andFIG. 28B, the cleaning section 4 includes a first cleaning chamber 190,a first transfer chamber 191, a second cleaning chamber 192, a secondtransfer chamber 193, and a drying chamber 194. In the first cleaningchamber 190, an upper primary cleaning module 201A and a lower primarycleaning module 201B are disposed. These primary cleaning modules 201Aand 201B are aligned along the vertical direction. Specifically, theupper primary cleaning module 201A is arranged above the lower primarycleaning module 201B. Similarly, an upper secondary cleaning module 202Aand a lower secondary cleaning module 202B are disposed in the secondcleaning chamber 192, and are aligned along the vertical direction. Theupper secondary cleaning module 202A is arranged above the lowersecondary cleaning module 202B. The first and secondary cleaning modules201A, 201B, 202A, and 202B are a cleaning machine for cleaning the waferusing a cleaning liquid. The arrangement of these cleaning modules 201A,201B, 202A, and 202B along the vertical direction presents an advantageof reducing a footprint.

A temporary base 203 for the wafer is provided between the uppersecondary cleaning module 202A and the lower secondary cleaning module202B. In the drying chamber 194, an upper drying module 205A and a lowerdrying module 205B are disposed along the vertical direction. The upperdrying module 205A and the lower drying module 205B are isolated fromeach other. Filter fan units 207 and 207 are provided on upper portionsof the upper drying module 205A and the lower drying module 205B so asto supply a clean air to these drying modules 205A and 205B,respectively. The upper primary cleaning module 201A, the lower primarycleaning module 201B, the upper secondary cleaning module 202A, thelower secondary cleaning module 202B, the temporary base 203, the upperdrying module 205A, and the lower drying module 205B are mounted onnon-illustrated frames via bolts or the like.

A vertically-movable first transfer robot 209 is provided in the firsttransfer chamber 191, and a vertically-movable second transfer robot 210is provided in the second transfer chamber 193. The first transfer robot209 and the second transfer robot 210 are movably supported byvertically-extending support shafts 211 and 212. The first transferrobot 209 and the second transfer robot 210 have drive mechanisms (e.g.,motors) therein, respectively, so that the transfer robots 209 and 210can move along the support shafts 211 and 212 in the verticaldirections. The first transfer robot 209 has vertically arranged twohands: an upper hand and a lower hand, as with the transfer robot 22.The first transfer robot 209 is located such that the lower hand thereofcan access the above-described temporary base 180, as indicated by adotted line in FIG. 28A. When the lower hand of the first transfer robot209 accesses the temporary base 180, a shutter (not shown in thedrawing) on the partition 1 b is opened.

The first transfer robot 209 is configured to transfer the wafer Wbetween the temporary base 180, the upper primary cleaning module 201A,the lower primary cleaning module 201B, the temporary base 203, theupper secondary cleaning module 202A, and the lower secondary cleaningmodule 202B. When transferring a wafer to be cleaned (i.e., a wafer withslurry attached), the first transfer robot 209 uses its lower hand. Onthe other hand, when transferring a cleaned wafer, the first transferrobot 209 uses its upper hand. The second transfer robot 210 isconfigured to transfer the wafer W between the upper secondary cleaningmodule 202A, the lower secondary cleaning module 202B, the temporarybase 203, the upper drying module 205A, and the lower drying module205B. The second transfer robot 210 transfers only a cleaned wafer, andthus has a single hand. The transfer robot 22 shown in FIG. 1 uses itsupper hand to remove the wafer from the upper drying module 205A or thelower drying module 205B, and returns the wafer to the wafer cassette.When the upper hand of the transfer robot 22 accesses the upper dryingmodule 205A or the lower drying module 205B, a shutter (not shown in thedrawing) on the partition 1 a is opened.

The cleaning section 4 has the two primary cleaning modules and the twosecondary cleaning modules, as described above. With this configuration,the cleaning section 4 can provide plural cleaning lines for cleaningplural wafers in parallel. The term “cleaning line” is a route of awafer in the cleaning section 4 when cleaned by the plural cleaningmodules. For example, in FIG. 29, a wafer can be transferred via thefirst transfer robot 209, the upper primary cleaning module 201A, thefirst transfer robot 209, the upper secondary cleaning module 202A, thesecond transfer robot 210, and the upper drying module 205A in thisorder (see a cleaning line 1). In parallel with this wafer route,another wafer can be transferred via the first transfer robot 209, thelower primary cleaning module 201B, the first transfer robot 209, thelower secondary cleaning module 202B, the second transfer robot 210, andthe lower drying module 205B in this order (see a cleaning line 2). Inthis manner, plural (typically two) wafers can be cleaned and driedsubstantially simultaneously by the two parallel cleaning lines.

It is also possible to clean and dry plural wafers at predetermined timeintervals in the two parallel cleaning lines. The advantages of cleaningthe wafers at predetermined time intervals are as follows. The firsttransfer robot 209 and the second transfer robot 210 are commonly usedin the plural cleaning lines. Accordingly, if cleaning processes ordrying processes are terminated at the same time, these transfer robotscannot transfer the wafers promptly. As a result, the throughput islowered. Such problems can be avoided by providing the predeterminedtime intervals when cleaning and drying plural wafers. With thisoperation, the processed wafers can be promptly transferred by thetransfer robots 209 and 210.

A polished wafer carries slurry attached thereto, and it is notpreferable to leave the polished wafer with the slurry attached for along time. This is because copper as interconnect metal could becorroded by the slurry. According to the cleaning section 4 with twoprimary cleaning modules, even when a preceding wafer is being cleanedin either of the upper primary cleaning module 201A or the lower primarycleaning module 201B, a following wafer can be transferred into anotherprimary cleaning module and can thus be cleaned. In this manner, thecleaning section 4 not only can achieve a high throughput, but it canalso prevent corrosion of the copper by rapidly cleaning the polishedwafer.

When only primary cleaning is necessitated, a wafer may be transferredvia the first transfer robot 209, the upper primary cleaning module201A, the first transfer robot 209, the temporary base 203, the secondtransfer robot 210, and the upper drying module 205A in this order asshown in FIG. 30, so that secondary cleaning in the second cleaningchamber 192 can be omitted. Further, as shown in FIG. 31, in a case of afailure in the lower primary cleaning module 201B, for example, thewafer can be transferred to the upper secondary cleaning module 202A. Inthis manner, the first transfer robot 209 and the second transfer robot210 can sort incoming wafers into predetermined cleaning lines asneeded. Selection of the cleaning lines is determined by the controller5.

Each of the cleaning modules 201A, 201B, 202A, and 202B has a detector(not shown in the drawing) for detecting a failure thereof. When afailure occurs in any of the cleaning modules 201A, 201B, 202A, and202B, the detector detects the failure, and sends a signal to thecontroller 5. The controller 5 selects a cleaning line that bypasses thebroken cleaning module, and switches a current cleaning line to anewly-selected cleaning line. While two primary cleaning modules and twosecondary cleaning modules are provided in this embodiment, the presentinvention is not limited to this arrangement. For example, three or moreprimary cleaning modules and/or three or more secondary cleaning modulesmay be provided.

A temporary base may be provided in the first cleaning chamber 190. Forexample, as with the temporary base 203, it is possible to install atemporary base between the upper primary cleaning module 201A and thelower primary cleaning module 201B. When one or some of the cleaningmodules break down, two wafers can be transferred to the temporary base180 (see FIG. 28A) and the temporary base in the first cleaning chamber190.

A concentration of the cleaning liquid to be used in the primarycleaning modules 201A and 201B may differ from a concentration of thecleaning liquid to be used in the secondary cleaning modules 202A and202B. For example, the concentration of the cleaning liquid to be usedin the primary cleaning modules 201A and 201B may be higher than theconcentration of the cleaning liquid to be used in the secondarycleaning modules 202A and 202B. Generally, a cleaning effect isconsidered to be substantially proportional to the concentration of thecleaning liquid and a cleaning time. Therefore, by using the cleaningliquid with a high concentration in the primary cleaning operation, aprimary cleaning time and a secondary cleaning time can be equalized,even when a wafer is badly stained.

In this embodiment, the primary cleaning modules 201A and 201B and thesecondary cleaning modules 202A and 202B are a roll-sponge-type cleaningmachine. The primary cleaning modules 201A and 201B and the secondarycleaning modules 202A and 202B have the same structure. Thus, only theprimary cleaning module 201A will be described below.

FIG. 32 is a perspective view showing the primary cleaning module 201A.As shown in FIG. 32, the primary cleaning module 201A has four rollers301, 302, 303, and 304 configured hold and rotate the wafer W, rollsponges (cleaning tools) 307 and 308 arranged to be brought into contactwith upper and lower surfaces of the wafer W, rotating mechanisms 310and 311 configured to rotate the roll sponges 307 and 308,cleaning-liquid supply nozzles 315 and 316 configured to supply acleaning liquid (e.g., pure water) onto the upper and lower surfaces ofthe wafer W, and etching-liquid supply nozzles 317 and 318 configured tosupply an etching liquid (e.g., a chemical liquid) onto the upper andlower surfaces of the wafer W. The rollers 301, 302, 303, and 304 aremoved closer to and away from each other by non-illustrated actuators(e.g., pneumatic cylinders).

The rotating mechanism 310 for rotating the upper roll sponge 307 ismounted on a guide rail 320 configured to guide a vertical movement ofthe rotating mechanism 310. Further, the rotating mechanism 310 issupported by an elevating mechanism 321, so that the rotating mechanism310 and the upper roll sponge 307 can be moved in the vertical directionby the elevating mechanism 321. Although not shown in the drawing, therotating mechanism 311 for rotating the lower roll sponge 308 is alsosupported by a guide rail, so that the rotating mechanism 311 and thelower roll sponge 308 can be moved in the vertical direction by anelevating mechanism. A pneumatic cylinder or a motor drive mechanismusing a ball screw may be used as the elevating mechanisms.

When the wafer W is carried in and out the primary cleaning module 201A,the roll sponges 307 and 308 are located away from each other. Whencleaning the wafer W, the roll sponges 307 and 308 are moved closer toeach other to contact the upper and lower surfaces of the wafer W.Forces of the roll sponges 307 and 308 pressing the upper and lowersurfaces of the wafer W are controlled by the elevating mechanism 321and the non-illustrated elevating mechanism. The upper roll sponge 307and the rotating mechanism 310 are supported by the elevating mechanism321 from below. Therefore, the pressing force of the upper roll sponge307 against the upper surface of the wafer W can be adjusted from 0 [N].

The roller 301 has a two-stage structure comprising a holding portion301 a and a shoulder (supporting portion) 301 b. The shoulder 301 b hasa diameter larger than a diameter of the holding portion 301 a. Theholding portion 301 a is formed on the shoulder 301 b. The rollers 302,303, and 304 have the same structure as the roller 301. The wafer W iscarried into the primary cleaning module 201A by the lower arm of thefirst transfer robot 209, and is placed onto the shoulders 301 b, 302 b,303 b, and 304 b. Then, the rollers 301, 302, 303, and 304 are movedtoward the wafer W to bring the holding portions 301 a, 302 a, 303 a,and 304 a into contact with the wafer W, whereby the wafer W is held bythe holding portions 301 a, 302 a, 303 a, and 304 a. At least one of thefour rollers 301, 302, 303, and 304 is rotated by a rotating mechanism(not shown in the drawing), whereby the wafer W is rotated with itsperiphery held by the rollers 301, 302, 303, and 304. The shoulders 301b, 302 b, 303 b, and 304 b comprise tapered surfaces with downwardgradient. With this configuration, the wafer W is kept out of contactwith the shoulders 301 b, 302 b, 303 b, and 304 b when the wafer W isheld by the holding portions 301 a, 302 a, 303 a, and 304 a.

Cleaning operation is performed as follows. First, the wafer W is heldby the rollers 301, 302, 303, and 304, and rotated. Subsequently, thecleaning liquid is supplied from the cleaning-liquid supply nozzles 315and 316 onto the upper surface and the lower surface of the wafer W.Then, the roll sponges 307 and 308 are rotated about their own axes andbrought into sliding contact with the upper and lower surfaces of thewafer W to thereby scrub the upper and lower surfaces of the wafer W.After the scrubbing process, the roll sponge 307 is moved upward and theroll sponge 308 is moved downward. Then, the etching liquid is suppliedfrom the chemical-liquid supply nozzles 317 and 318 onto the uppersurface and the lower surface of the wafer W to perform etching(chemical cleaning) of the upper and lower surfaces of the wafer W.

The upper primary cleaning module 201A, the lower primary cleaningmodule 201B, the upper secondary cleaning module 202A, and the lowersecondary cleaning module 202B may be of the same type or may be ofdifferent types. For example, the primary cleaning modules 201A and 201Bmay be the above-described cleaning machine having a pair of rollsponges for scrubbing the upper and lower surfaces of the wafer, and thesecondary cleaning modules 202A and 202B may be cleaning machine of apencil-sponge type or two-fluid-jet type. The two-fluid-jet-typecleaning machine is configured to produce a mixture of an N₂ gas andpure water (DIW), containing a small amount of CO₂ gas (carbon dioxidegas) dissolved therein, and eject the mixture of the N₂ gas and the purewater onto the surface of the wafer. This type of cleaning machine canremove fine particles on the wafer by fine droplets and impact energy.In particular, wafer cleaning with no damage can be realized byappropriately adjusting a flow rate of the N₂ gas and a flow rate of thepure water. Further, use of the pure water containing the carbon dioxidegas therein can prevent corrosion of the wafer that could be caused bystatic electricity.

Each of the drying modules 205A and 205B has a substrate holdingmechanism for holding and rotating a wafer, and is configured to dry thewafer while rotating the wafer by the substrate holding mechanism. Next,the substrate holding mechanism will be described. FIG. 33 is a verticalcross-sectional view showing the substrate holding mechanism, and FIG.34 is a plan view showing the substrate holding mechanism. As shown inFIG. 33 and FIG. 34, the substrate holding mechanism includes a base 401having four arms 401 a, and four cylindrical substrate-support members402 which are vertically movably supported by tip ends of the arms 401a. The base 401 is secured to an upper end of a rotational shaft 405,which is rotatably supported by bearings 406. These bearings 406 aresecured to an inner surface of a cylindrical member 407 which is inparallel with the rotational shaft 405. A lower end of the cylindricalmember 407 is mounted on a mount base 409 and is fixed in position. Themount base 409 is secured to a frame 410. The rotational shaft 405 iscoupled to a motor 415 via pulleys 411 and 412 and a belt 414, so thatthe base 401 is rotated about its own axis by the motor 415.

A lifting mechanism 470 for elevating the substrate-support members 402is provided around the cylindrical member 407. This lifting mechanism470 is configured to be able to slide in the vertical direction relativeto the cylindrical member 407. The lifting mechanism 470 includescontact plates 470 a arranged to be brought into contact with lower endsof the substrate-support members 402. A first gas chamber 471 and asecond gas chamber 472 are formed between an outer circumferentialsurface of the cylindrical member 407 and an inner circumferentialsurface of the lifting mechanism 470. The first gas chamber 471 and thesecond gas chamber 472 are in fluid communication with a first gaspassage 474 and a second gas passage 475, respectively. The first gaspassage 474 and the second gas passage 475 have their ends which arecoupled to a pressurized-gas supply source (not shown in the drawing).When pressure in the first gas chamber 471 is increased higher thanpressure in the second gas chamber 472, the lifting mechanism 470 iselevated, as shown in FIG. 35. On the other hand, when pressure in thesecond gas chamber 472 is increased higher than pressure in the firstgas chamber 471, the lifting mechanism 470 is lowered, as shown in FIG.33.

FIG. 36A is a plan view showing part of the substrate-support member 402and the arm 401 a shown in FIG. 34, FIG. 36B is a cross-sectional viewtaken along line A-A shown in FIG. 34, and FIG. 36C is a cross-sectionalview taken along line B-B shown in FIG. 36B. The arm 401 a of the base401 has a holder 401 b configured to slidably hold the substrate-supportmember 402. This holder 401 b may be formed integrally with the arm 401a. A vertically-extending through-hole is formed in the holder 401 b,and the substrate-support member 402 is inserted in this through-hole.The through-hole has a diameter slightly larger than a diameter of thesubstrate-support member 402. Therefore, the substrate-support member402 is movable in the vertical direction relative to the base 401, andthe substrate-support member 402 is rotatable about its own axis.

A spring support 402 a is attached to a lower portion of thesubstrate-support member 402. A spring 478 is disposed around thesubstrate-support member 402, and the spring 478 is supported by thespring support 402 a. An upper end of the spring 478 presses the holder401 b (which is part of the base 401). Therefore, the spring 478 exertsa downward force on the substrate-support member 402. A stopper 402 b isformed on a circumferential surface of the substrate-support member 402.This stopper 402 b has a diameter larger than the diameter of thethrough-hole. Therefore, a downward movement of the substrate-supportmember 402 is limited by the stopper 402 b, as shown in FIG. 36B.

A support pin 479 on which the wafer W is to be placed and a cylindricalclamp 480 as a substrate holding portion to be brought into contact withthe periphery of the wafer W are provided on an upper end of thesubstrate-support member 402. The support pin 479 is arranged on theaxis of the substrate-support member 402. On the other hand, the clamp480 is arranged away from the axis of the substrate-support member 402.Therefore, as the substrate-support member 402 rotates, the clamp 480makes revolutions around the axis of the substrate-support member 402.In order to prevent electrostatic charge, wafer-contacting portions arepreferably made from a conductive material (preferably iron, aluminum,SUS) or carbon resin (e.g., PEEK or PVC).

A first magnet 481 is attached to the holder 401 b of the base 401 so asto face a side surface of the substrate-support member 402. On the otherhand, a second magnet 482 and a third magnet 483 are provided in thesubstrate-support member 402. The second magnet 482 and the third magnet483 are arranged away from each other in the vertical direction.Neodymium magnet is preferably used as the first, second, and thirdmagnets 481, 482, and 483.

FIG. 37 is a schematic view showing an arrangement of the second magnet482 and the third magnet 483, as viewed from the axial direction of thesubstrate-support member 402. As shown in FIG. 37, the second magnet 482and the third magnet 483 are arranged in different positions withrespect to the circumferential direction of the substrate-support member402. Specifically, a line connecting the second magnet 482 and thecenter of the substrate-support member 402 and a line connecting thethird magnet 483 and the center of the substrate-support member 402cross at a predetermined angle of α.

When the substrate-support member 402 is in the lowered position asshown in FIG. 36B, the first magnet 481 and the second magnet 482 faceeach other. At this time, an attractive force acts between the firstmagnet 481 and the second magnet 482. This attractive force generates aforce of rotating the substrate-support member 402 about its own axis ina direction such that the clamp 480 presses the periphery of the waferW. Accordingly, the lowered position shown in FIG. 36B is a clampposition in which the wafer W is held (clamped).

It is not necessary that the first magnet 481 and the second magnet 482always face each other when holding the wafer W, as long as they areclose enough to produce a sufficient holding force. For example, evenwhen the first magnet 481 and the second magnet 482 tilt with respect toeach other, the magnet force is produced between these magnets, as longas they are close to each other. Therefore, it is not necessary that thefirst magnet 481 and the second magnet 482 always face each other whenholding the wafer W, as long as the magnet force is large enough torotate the substrate-support member 402 to hold the wafer W.

FIG. 38A is a plan view showing part of the substrate-support member 402and the arm 401 a when the substrate-support member 402 is elevated bythe lifting mechanism 470, and FIG. 38B is a cross-sectional view takenalong line A-A shown in FIG. 34 when the substrate-support member 402 iselevated by the lifting mechanism 470, and FIG. 38C is a cross-sectionalview taken along line C-C shown in FIG. 38B.

When the substrate-support member 402 is elevated by the liftingmechanism 470 to the elevated position as shown in FIG. 38B, the firstmagnet 481 and the third magnet 483 face each other, and the secondmagnet 482 is away from the first magnet 481. At this time, anattractive force acts between the first magnet 481 and the third magnet483. This attractive force generates a force of rotating thesubstrate-support member 402 about its own axis in a direction such thatthe clamp 480 moves away from the wafer W. Accordingly, the elevatedposition shown in FIG. 38B is an unclamp position in which the wafer Wis released (unclamped). In this case also, it is not necessary that thefirst magnet 481 and the third magnet 483 always face each other whenreleasing the wafer W, as long as they are close enough to produce asufficient force (magnet force) of rotating the substrate-support member402 in a direction such that the clamp 480 is moved away from the waferW.

Because the second magnet 482 and the third magnet 483 are arranged indifferent positions with respect to the circumferential direction of thesubstrate-support member 402, the rotating force acts on thesubstrate-support member 402 as the substrate-support member 402 movesup and down. This rotating force provides the clamp 480 with a force ofholding the wafer W and a force of releasing the wafer W. Therefore,just by moving the substrate-support member 402 vertically, the clamp480 can hold and release the wafer W. In this manner, the first magnet481, the second magnet 482, and the third magnet 483 functions as aholding mechanism (rotating mechanism) for rotating thesubstrate-support member 402 about its own axis to cause the clamp 480to hold the wafer W. This holding mechanism (rotating mechanism) isoperated by the vertical movements of the substrate-support member 402.

The contact plates 470 a of the lifting mechanism 470 are located belowthe substrate-support members 402. When the contact plates 470 a moveupward, upper surfaces of the contact plates 470 a are brought intocontact with the lower ends of the substrate-support members 402, andthe substrate-support members 402 are elevated by the contact plates 470a against the pressing forces of the springs 478. The upper surface ofeach contact plate 470 a is a flat surface, and on the other hand, thelower end of each substrate-support member 402 is in the shape ofhemisphere. In this embodiment, the lifting mechanism 470 and thesprings 478 constitute a drive mechanism for moving thesubstrate-support members 402 in the vertical direction. It is to benoted that the drive mechanism is not limited to this embodiment. Forexample, a servomotor may be used as the drive mechanism.

FIG. 39A is a side view showing the substrate-support member 402 in theclamp position as viewed from a different angle, and FIG. 39B is across-sectional view taken along line D-D shown in FIG. 39A. FIG. 40A isa side view showing the substrate-support member 402 in the unclampposition as viewed from a different angle, and FIG. 40B is across-sectional view taken along line E-E shown in FIG. 40A.

A groove 484 is formed on the side surface of each substrate-supportmember 402. This groove 484 extends along the axis of thesubstrate-support member 402, and has an arc-shaped horizontal crosssection. A protrusion 485 projecting toward the groove 484 is formed onthe arm 401 a (the holder 401 b in this embodiment) of the base 401. Atip end of this protrusion 485 lies in the groove 484, and theprotrusion 485 roughly engages the groove 484.

The groove 484 and the protrusion 485 are provided for limiting arotation angle of the substrate-support member 402. More specifically,as shown in FIG. 39B and FIG. 40B, when the substrate-support member 402rotates between the clamp position and the unclamp position, theprotrusion 485 does not contact the groove 484. Therefore, thesubstrate-support member 402 can freely rotate by the magnetic forceacting between the above-described magnets. On the other hand, when thesubstrate-support member 402 rotates beyond the clamp position and theunclamp position, the protrusion 485 contacts the groove 484 to therebyprevent the substrate-support member 402 from rotating excessively. Inthis manner, the protrusion 485 and the groove 484 function as astopper. Therefore, when the substrate-support member 402 moves upwardand downward, either of the second magnet 482 or the third magnet 483 isnecessarily located adjacent to the first magnet 481.

Next, operations of the above-substrate holding mechanism will bedescribed.

When the substrate holding mechanism is in the unclamp position as shownin FIG. 38B, the wafer W is placed onto the support pins 479 by thetransfer robot. Then, the lifting mechanism 470 is lowered. Thesubstrate-support members 402 are lowered by the springs 478 to theclamp position as shown in FIG. 36B. While the substrate-support members402 are lowered, the second magnets 482 face the first magnets 481,whereby the substrate-support members 402 rotate. The rotation of thesubstrate-support members 402 brings side surfaces of the clamps 480into contact with the periphery of the wafer W, whereby the wafer W isheld by the clamps 480. A tip end of the support pin 479 has a verysmall contact area with the wafer W, and similarly the side surface ofthe clamp 480 has a very small contact area with the wafer W. Therefore,contamination of the wafer W due to contact with other components can beprevented. In order to prevent electrostatic charge, a conductivematerial (preferably iron, aluminum, SUS) or carbon resin (e.g., PEEK orPVC) is preferably used as the wafer contact portions.

When the motor 415 is set in motion, the wafer W rotates together withthe substrate-support members 402. When the rotation is stopped,positioning (or alignment) between the four substrate-support members402 and the four contact plates 470 a of the lifting mechanism 470 isperformed. Specifically, the rotation of the base 401 is stopped at aposition such that the substrate-support members 402 are located abovethe contact plates 470 a. When the substrate-support members 402 areelevated by the lifting mechanism 470, the substrate-support members 402are rotated about their own axes to cause the clamps 480 to move awayfrom the wafer W. As a result, the wafer W is released and just placedon the support pins 479. In this state, the wafer W is removed from thesubstrate holding mechanism by the transfer robot.

FIG. 41A is an enlarged plan view showing a modified example of thesubstrate-support member 402 and the clamp (substrate holding portion)480, and FIG. 41B is a side view showing the substrate-support member402 and the clamp 480 shown in FIG. 41A. FIG. 41A and FIG. 41B show onlypart of the substrate-support member 402.

Cylindrical clamp 480 and a positioning portion 488 are provided on theupper end of substrate-support member 402. The clamp 480 is a substrateholding portion to be brought into contact with the periphery of thewafer W. The positioning portion 488 extends from the clamp 480 to theaxis of the substrate-support member 402. One end of the positioningportion 488 is connected integrally to the side surface of the clamp480, and the other end is located on the axis of the substrate-supportmember 402. This center-side end of the positioning portion 488 has aside surface 488 a curved along a circle which is concentric with thesubstrate-support member 402. Specifically, a horizontal cross sectionof the center-side end of the positioning portion 488 is formed by partof the circle that is concentric with the substrate-support member 402.The upper end of the substrate-support member 402 comprises a taperedsurface with a downward gradient.

FIG. 42A is a plan view showing a state in which the wafer is clamped,and FIG. 42B is a plan view showing a state in which the wafer isunclamped. The wafer W is placed onto the upper ends (i.e., the taperedsurfaces) of the substrate-support members 402 and then thesubstrate-support members 402 are rotated to bring the clamps 480 intocontact with the periphery of the wafer W, whereby the wafer W is heldby the clamps 480, as shown in FIG. 42A. When the substrate-supportmembers 402 are rotated in the opposite direction, the clamps 480 aremoved away from the wafer W as shown in FIG. 42B, whereby the wafer W isreleased. During the rotation of the substrate-support members 402, theperiphery of the wafer W is placed in sliding contact with the sidesurfaces 488 a of the positioning portions 488. The side surfaces 488 aof the positioning portions 488 can prevent displacement of the wafer Wduring the rotation of the substrate-support members 402. As a result,the subsequent wafer transferring operations can be performed stably.

FIG. 43A is a cross-sectional view showing a modified example of part ofthe substrate holding mechanism, and FIG. 43B is a side view showing asubstrate-support member. Configurations and operations of this modifiedexample, except for the following configurations which will be describedbelow, are identical to those of the above-described substrate holdingmechanism, and will not be described repetitively.

A helical groove 490 is formed on a side surface of substrate-supportmember 402. This helical groove 490 has a portion slightly inclined withrespect to the axis of the substrate-support member 402. The helicalgroove 490 has an upper portion and a lower portion extending parallelto the axis of the substrate-support member 402. A pin 491, whichroughly engages the helical groove 490, is provided on the holder 401 b.With this configuration, as the substrate-support member 402 movesupward and downward, the substrate-support member 402 rotates about itsown axis through a predetermined angle due to the engagement of thehelical groove 490 and the pin 491. The rotation of thesubstrate-support member 402 causes the clamp 480 to contact or moveaway from the periphery of the wafer W. Therefore, in this example, thehelical groove 490 and the pin 491 functions as a holding mechanism(rotating mechanism) for rotating the substrate-support member 402 aboutits own axis to cause the clamp 480 to hold the wafer W. This holdingmechanism (rotating mechanism) is operated by the vertical movements ofthe substrate-support member 402.

FIG. 44 is a vertical cross-sectional view showing an example in which aspin cover 450 is attached to the substrate holding mechanism. A lefthalf of FIG. 44 shows a state in which the wafer is clamped, and a righthalf shows a state in which the wafer is unclamped. In FIG. 44, therotational shaft 405, the cylindrical member 407, the lifting mechanism470, and other elements are illustrated schematically, but the detailedstructures thereof are as shown in FIG. 33. In FIG. 44, a vertical crosssection of the spin cover 450 is illustrated.

As shown in FIG. 44, the spin cover 450 is secured to an upper surfaceof the base 401 and is arranged so as to surround the wafer W. The spincover 450 has the vertical cross section that is inclined radiallyinwardly. An upper end of the spin cover 450 lies in close proximity tothe wafer W, and an inside diameter of the upper end of the spin cover450 is slightly larger than the diameter of the wafer W. The upper endof the spin cover 450 has notches 450 a each shaped along thecircumferential surface of the substrate-support member 402. The notches450 a are located in positions corresponding to the substrate-supportmembers 402. Drain holes 451, which extend obliquely, are formed in abottom of the spin cover 450.

The substrate holding mechanism with the spin cover 450 attached theretois suitable for use in a substrate cleaning apparatus and a substratedrying apparatus using a liquid. For example, the above-describedsubstrate holding mechanism can be used in a substrate cleaningapparatus for cleaning a wafer by supplying a cleaning liquid onto anupper surface of the wafer. The cleaning liquid (e.g., pure water),supplied to the upper surface of the wafer, is spun off from theperiphery of the wafer by the centrifugal force, and is captured by aninner circumferential surface of the spin cover 450 that is in rotationat the same speed as the wafer. Because the inner circumferentialsurface of the spin cover 450 is inclined, the cleaning liquid is forcedto flow downward by the centrifugal force, and then expelled downwardthrough the drain holes 451 of the spin cover 450. In this manner,because the spin cover 450 and the wafer rotate in unison, the liquidhardly bounces back onto the wafer. Therefore, production of watermarkson the wafer can be prevented. In the wafer cleaning operation using thesubstrate holding mechanism shown in FIG. 44, the clamps 480 on thesubstrate-support members 402 press the wafer W to hold the wafer W, thecleaning liquid is supplied onto the wafer W to clean the wafer W whilerotating the wafer W, and the substrate-support members 402 are elevatedto cause the clamp 480 to move away from the wafer W. A series of theseoperations can be performed by the vertical movement of thesubstrate-support members 402 without exerting a mechanical adverseinfluence on the wafer W during cleaning of the wafer.

The above-described substrate holding mechanism can be used in varioustypes of processing apparatus, in addition to the substrate cleaningapparatus. For example, the substrate holding mechanism shown in FIG. 44can be used in a drying apparatus of Rotagoni type. The Rotagoni dryingmethod is a method of drying a surface of a wafer by supplying an IPAvapor (a mixture of isopropyl alcohol and an N₂ gas) and pure water fromtwo parallel nozzles to the surface of the rotating wafer while movingthe two nozzles along a radial direction of the wafer. This Rotagonidrying method has recently been drawing attention as a drying methodcapable of preventing the production of the water marks on the surfaceof the wafer. In the wafer drying operation using the substrate holdingmechanism shown in FIG. 44, the clamps 480 on the substrate-supportmembers 402 press the wafer W to hold the wafer W, the IPA vapor issupplied onto the wafer W to dry the wafer W while rotating the wafer W,and the substrate-support members 402 are elevated to cause the clamp480 to move away from the wafer W. A series of these operations can beperformed by the vertical movement of the substrate-support members 402without exerting a mechanical adverse influence on the wafer W duringdrying of the wafer. Further, an effect of the droplets scattered by thecentrifugal force can be reduced during drying.

The above-described substrate holding mechanism is configured such thatall of the four substrate-support members 402 are rotated to produce thesubstrate holding force. Alternatively, two of the foursubstrate-support members 402 may be only movable in the verticaldirection and may not be rotatable about their own axes. In this case,the non-rotatable two substrate-support members can be used inpositioning of the wafer. The number of substrate-support members may bethree, or five or more. In a case of providing three substrate-supportmembers, the above-described rotating mechanism (magnets or helicalgroove) may be provided only on one of the three substrate-supportmembers.

Further, while the first magnet 481 is attached to the base 401 and thesecond magnet 482 and the third magnet 483 are attached to thesubstrate-support member 402 in the above embodiment, the presentinvention is not limited to this arrangement. For example, the firstmagnet 481 may be attached to the substrate-support member 402, and thesecond magnet 482 and the third magnet 483 may be attached to the base401.

Next, the details of the upper drying module 205A and the lower dryingmodule 205B each including the above-described substrate holdingmechanism will be described. The upper drying module 205A and the lowerdrying module 205B are a drying machine that performs the Rotagonidrying operation. Since the upper drying module 205A and the lowerdrying module 205B have the same structure, the upper drying module 205Awill be described below. FIG. 45 is a vertical cross-sectional viewshowing the upper drying module 205A, and FIG. 46 is a plan view showingthe upper drying module 205A.

A front nozzle 454 for supplying pure water as a cleaning liquid ontothe surface (front surface) of the wafer W is arranged above the waferW. The front nozzle 454 is oriented toward the center of the substrateW. The front nozzle 454 is coupled to a pure water supply source (i.e.,a cleaning liquid supply source), not shown in the drawings, andsupplies the pure water to the center of the front surface of the waferW. Other than pure water, a chemical liquid may be used as the cleaningliquid. Two parallel nozzles 460 and 461 for performing Rotagoni dryingare disposed above the wafer W. The nozzle 460 is for supplying an IPAvapor (a mixture of isopropyl alcohol and an N₂ gas) onto the frontsurface of the wafer W. The nozzle 461 is for supplying pure water ontothe front surface of the wafer W in order to prevent the front surfaceof the wafer W from being dried. The nozzles 460 and 461 are movable inthe radial direction of the wafer W.

The rotational shaft 405 houses therein a back nozzle 463 coupled to acleaning-liquid supply source 465 and a gas nozzle 464 coupled to adrying-gas supply source 466. The cleaning-liquid supply source 465stores pure water as a cleaning liquid therein and supplies the purewater through the back nozzle 463 to a rear surface of the wafer W. Thedrying-gas supply source 466 stores an N₂ gas or dry air as a drying gastherein, and supplies the drying gas through the gas nozzle 464 to therear surface of the wafer W.

FIG. 47 is an IPA supply unit for supplying the IPA vapor (a mixture ofisopropyl alcohol and the N₂ gas) to the nozzle 460. This IPA supplyunit is installed in the substrate processing apparatus. As shown inFIG. 47, the IPA supply unit includes a bubbling tank 501 made of metal,such as stainless steel. Inside the bubbling tank 501, a bubbler 502 forcreating bubbles of the N₂ gas is installed on a bottom of the bubblingtank 501. This bubbler 502 is coupled to an N₂ gas bubbling line 503,which is coupled to an N₂ gas introduction line 504. This N₂ gasintroduction line 504 is coupled to an N₂ gas supply source 505.Regulating valves 514 and 515 are provided on the N₂ gas introductionline 504 and the N₂ gas bubbling line 503.

A mass flow controller 520 and a filter 521 are provided on the N₂ gasbubbling line 503. The N₂ gas is supplied from the N₂ gas supply source505 to the bubbler 502 via the N₂ gas introduction line 504, the N₂ gasbubbling line 503, and the filter 521. A flow rate of the N₂ gas is keptconstant by the mass flow controller 520. The preferable flow rate ofthe N₂ gas to the bubbler 502 is in the range of about 0 to 10 SLM. Theterm “SLM” is an abbreviation of “Standard Litter per Minute” and is aunit expressing a flow rate of a gas at a temperature of 0 degree under1 atm.

An IPA liquid supply line 506 and an IPA vapor delivery line 507 arefurther coupled to the bubbling tank 501. The IPA vapor delivery line507 is coupled to the nozzles 460 (see FIG. 45) of the upper dryingmodule 205A and the lower drying module 205B through a filter 522. TheIPA liquid supply line 506 is coupled to an IPA supply source 508, whichsupplies an IPA liquid (isopropyl alcohol) to the bubbling tank 501through the IPA liquid supply line 506. A liquid-level sensor (not shownin the drawing) is provided in the bubbling tank 501 for detecting aliquid level of the IPA liquid in the bubbling tank 501. A regulatingvalve 516 is provided on the IPA liquid supply line 506. This regulatingvalve 516 is operated so as to regulate a flow rate of the IPA liquid tobe supplied to the bubbling tank 501 such that an output signal of theliquid-level sensor (i.e., the level of the IPA liquid in the bubblingtank 501) is maintained within a predetermined range. For example, theIPA liquid in the range of 200 mL to 700 mL is stored in the bubblingtank 501.

Generally, when bubbling is continuously performed, a temperature of theIPA liquid in the bubbling tank 501 is lowered due to heat ofvaporization of IPA. The drop in the temperature of the IPA liquidcauses a decrease in concentration of the IPA vapor, which can result ina failure in stable drying of the wafer. Thus, in order to keep thetemperature of the IPA liquid constant, a water jacket 510 is providedaround the bubbling tank 501. Heating water is supplied to the waterjacket 510 and flows through the water jacket 510, whereby thetemperature of the IPA liquid retained in the bubbling tank 501 is keptconstant. The heating water flows into the water jacket 510 through aninlet on a lower portion of the water jacket 510 and flows out throughan outlet on an upper portion of the water jacket 510. A preferable flowrate of the heating water flowing through the water jacket 510 is in therange of 50 mL/min to 200 mL/min, and a preferable temperature of theheating water is in the range of 22 to 25 degrees. In this embodiment,DIW (ultra pure water) is used as the heating water. However, othermedium may be used.

Bubbling of the N₂ gas in the IPA liquid generates the IPA vapor, whichis stored in an upper space in the bubbling tank 501. This IPA vapor isdelivered to the nozzles 460 (see FIG. 45) of the upper drying module205A and the lower drying module 205B through the IPA vapor deliveryline 507 and the filter 522. By passing the IPA vapor through the filter522, the IPA vapor to be supplied to the wafer is kept clean. Apreferable temperature of the IPA vapor is in the range of 18 to 25degrees. This temperature range is determined in view of preventing athermal stress on the wafer.

A preferable concentration of the IPA vapor produced in the bubblingtank 501 is in the range of about 0 to 4 vol %. When the temperature ofthe heating water itself is increased, the temperature of the IPA liquidin the bubbling tank 501 is increased. As a result, the concentration ofthe evaporated IPA is increased. Therefore, the concentration of the IPAvapor can be adjusted by the temperature of the heating water. Theadvantage of using the heating water for heating the IPA liquid is thatno electric heat source, such as a heater, is used in the substrateprocessing apparatus and therefore safety of the substrate processingapparatus can be secured.

An N₂ dilution line 525 is provided as a bypass line coupling the N₂ gasintroduction line 504 to the IPA vapor delivery line 507. A mass flowcontroller 527, a regulating valve 528, and a check valve 529 areprovided on the N₂ dilution line 525. The IPA vapor can be diluted withthe N₂ gas by directly delivering the N₂ gas to the IPA vapor deliveryline 507 through the N₂ dilution line 525. A flow rate of the N₂ gas tobe delivered to the IPA vapor delivery line 507 is controlled by themass flow controller 527.

An IPA relief line 530 is connected to the upper portion of the bubblingtank 501. A regulating valve 532, a check valve 533, and a release valve534 are provided on the IPA relief line 530. The regulating valve 532and the release valve 534 are arranged in parallel. When pressure in thebubbling tank 501 exceeds a certain value, the release valve 534 isopened to release the IPA vapor in the bubbling tank 501 into theexterior of the bubbling tank 501. Further, when the bubbling tank 501is replenished with IPA, the regulating valve 532 is opened to place theinterior of the bubbling tank 501 under the atmospheric pressure. Theregulating valves 515 and 528 may be shut-off valves. In this case, theflow rate of the N₂ gas is regulated by the mass flow controllers 520and 527, and on the other hand, the flow of the N₂ gas is shut off bythe shut-off valves 515 and 528.

Next, operations of the drying module 205A with the above-describedstructures will be described.

First, the wafer W and the spin cover 450 are rotated in unison by themotor 415. In this state, the front nozzle 454 and the back nozzle 463supply the pure water onto the front surface (upper surface) and therear surface (lower surface) of the wafer W so as to rinse the wafer Win its entirety with the pure water. The pure water, supplied to thewafer W, spreads over the front surface and the rear surface via thecentrifugal force, thereby rinsing all the surfaces of the wafer W. Thepure water, that is spun off from the rotating wafer W, is captured bythe spin cover 450 and flows into the drain holes 451. When the wafer Wis rinsed, the two nozzles 460 and 461 are in their given idle positionsaway from the wafer W.

Then, supply of the pure water from the front nozzle 454 is stopped, andthe front nozzle 454 is moved to its given idle position away from thewafer W. The two nozzles 460 and 461 are moved to their operatingpositions above the wafer W. While the wafer W is being rotated at a lowspeed ranging from 30 to 150 min⁻¹, the nozzle 460 supplies the IPAvapor and the nozzle 461 supplies the pure water onto the front surfaceof the wafer W. During this operation, the back nozzle 463 supplies thepure water to the rear surface of the wafer W. The two nozzles 460 and461 are simultaneously moved in the radial direction of the wafer W,whereby the front surface (upper surface) of the wafer W is dried.

Thereafter, the two nozzles 460 and 461 are moved to the their idlepositions, and supply of the pure water from the back nozzle 463 isstopped. Then, the wafer W is rotated at a high speed ranging from 1000to 1500 min⁻¹, thereby removing the pure water from the rear surface ofthe wafer W. During this operation, the gas nozzle 464 supplies thedrying gas to the rear surface of the wafer W. In this manner, the rearsurface of the wafer W is dried. The dried wafer W is removed from thedrying module 205A by the transfer robot 22 shown in FIG. 1, andreturned to the wafer cassette. In this manner, a series of processesincluding polishing, cleaning, and drying of the wafer is performed. Thedrying module 205A according to the above-described structures can dryboth upper and lower surfaces of the wafer W promptly and effectively,and can accurately controls an endpoint of the drying operation.Therefore, the drying process does not become a rate-limiting step inthe overall cleaning process. Moreover, because the processing times inthe multiple cleaning lines formed in the cleaning section 4 can beequalized, the throughput of the processes in their entirety can beimproved.

The previous description of embodiments is provided to enable a personskilled in the art to make and use the present invention. Moreover,various modifications to these embodiments will be readily apparent tothose skilled in the art, and the generic principles and specificexamples defined herein may be applied to other embodiments. Therefore,the present invention is not intended to be limited to the embodimentsdescribed herein but is to be accorded the widest scope as defined bylimitation of the claims and equivalents.

What is claimed is:
 1. An apparatus for processing a substrate, saidapparatus comprising: a polishing section configured to polish asubstrate; a transfer mechanism configured to transfer the substrate;and a cleaning section configured to clean and dry the polishedsubstrate, said cleaning section having plural cleaning lines forcleaning plural substrates, wherein said plural cleaning lines includeplural primary cleaning modules for performing a primary cleaningoperation on the substrate and plural secondary cleaning modules forperforming a secondary cleaning operation on the substrate, and whereinsaid plural primary cleaning modules are aligned along a verticaldirection and said plural secondary cleaning modules are aligned along avertical direction.
 2. The apparatus according to claim 1, wherein saidcleaning section includes a sorting mechanism configured to sort thepolished substrates into said plural cleaning lines.
 3. The apparatusaccording to claim 1, wherein said cleaning section includes a firsttransfer robot which can access said plural primary cleaning modules andsaid plural secondary cleaning modules, and a second transfer robotwhich can access said plural secondary cleaning modules.
 4. Theapparatus according to claim 3, further comprising: a detectorconfigured to detect failure of any one of said plural primary cleaningmodules and said plural secondary cleaning modules; and a controllerconfigured to select a cleaning line bypassing a broken cleaning modulewhich is detected by said detector, said broken cleaning module beingone of said plural primary cleaning modules and said plural secondarycleaning modules, and said controller being configured to switch acurrent cleaning line, including the broken cleaning module, to theselected cleaning line.
 5. The apparatus according to claim 3, furthercomprising: a controller configured to select a cleaning line bypassinga busy cleaning module which is cleaning a preceding substrate, saidbusy cleaning module being one of said plural primary cleaning modulesand said plural secondary cleaning modules, and said controller beingconfigured to control said first transfer robot or said second transferrobot so as to clean the substrate in the selected cleaning line.
 6. Theapparatus according to claim 3, wherein said cleaning section includes atemporary base on which the substrate is placed temporarily, and theapparatus further comprising a controller configured to control saidfirst transfer robot such that said first transfer robot transports thesubstrate to said temporary base and further transports the substratefrom said temporary base to one of said plural secondary cleaningmodules to thereby skip the primary cleaning operation on the substratein any one of said plural primary cleaning modules.
 7. The apparatusaccording to claim 3, wherein said cleaning section includes a temporarybase on which the substrate is placed temporarily, and the apparatusfurther comprises a controller configured to control said first transferrobot and said second transfer robot such that said first transfer robottransports the substrate from one of said plural primary cleaningmodules to said temporary base and said second transfer robot removesthe substrate from said temporary base to thereby skip the secondarycleaning operation on the substrate in any one of said plural secondarycleaning modules.
 8. The apparatus according to claim 1, wherein saidplural cleaning lines include a temporary base on which the substrate isplaced temporarily.
 9. The apparatus according to claim 1, wherein saidcleaning section includes plural drying modules for drying the pluralsubstrates cleaned by said plural cleaning lines.
 10. The apparatusaccording to claim 9, wherein said plural drying modules are alignedalong a vertical direction.
 11. The apparatus according to claim 1,wherein said cleaning section includes a first transfer robot and asecond transfer robot each configured to sort the polished substratesinto said plural cleaning lines.
 12. The apparatus according to claim11, wherein: said first transfer robot is configured to move in thevertical direction along a vertically-extending first support shaft tobe able to access said plural primary cleaning modules and said pluralsecondary cleaning modules; and said second transfer robot is configuredto move in the vertical direction along a vertically-extending secondsupport shaft to be able to access said plural secondary cleaningmodules.
 13. The apparatus according to claim 12, wherein each of saidplural primary cleaning modules is configured to perform the primarycleaning operation on the substrate while supplying a cleaning liquidonto the substrate, and each of said plural secondary cleaning modulesis configured to perform the secondary cleaning operation on thesubstrate while supplying the cleaning liquid, having a lowerconcentration than that in the primary cleaning operation, onto thesubstrate.
 14. The apparatus according to claim 12, wherein each of saidplural primary cleaning modules is configured to perform the primarycleaning operation for a first cleaning time, and each of said pluralsecondary cleaning modules is configured to perform the secondarycleaning operation for a second cleaning time that is substantiallyequal to the first cleaning time.
 15. The apparatus according to claim12, further comprising: a detector configured to detect failure of anyone of said plural primary cleaning modules and said plural secondarycleaning modules; and a controller configured to select a cleaning linethat bypasses a broken cleaning module which is detected by saiddetector, said broken cleaning module being one of said plural primarycleaning modules and said plural secondary cleaning modules, and saidcontroller being configured to switch a current cleaning line, includingthe broken cleaning module, to the selected cleaning line.
 16. Theapparatus according to claim 1, wherein said plural cleaning lines arearranged in parallel.
 17. An apparatus for processing a substrate, saidapparatus comprising: a polishing section configured to polish asubstrate; a transfer mechanism configured to transfer the substrate;and a cleaning section configured to clean and dry the polishedsubstrate, said cleaning section having plural cleaning lines forcleaning plural substrates, wherein said plural cleaning lines includeplural primary cleaning modules for performing a primary cleaningoperation on the substrate and plural secondary cleaning modules forperforming a secondary cleaning operation on the substrate, and saidcleaning section includes a first transfer robot which can access saidplural primary cleaning modules and said plural secondary cleaningmodules, and a second transfer robot which can access said pluralsecondary cleaning modules.
 18. The apparatus according to claim 17,further comprising: a detector configured to detect failure of any oneof said plural primary cleaning modules and said plural secondarycleaning modules; and a controller configured to select a cleaning linebypassing a broken cleaning module which is detected by said detector,said broken cleaning module being one of said plural primary cleaningmodules and said plural secondary cleaning modules, and said controllerbeing configured to switch a current cleaning line, including the brokencleaning module, to the selected cleaning line.
 19. The apparatusaccording to claim 17, further comprising: a controller configured toselect a cleaning line bypassing a busy cleaning module which iscleaning another substrate, said busy cleaning module being one of saidplural primary cleaning modules and said plural secondary cleaningmodules, and said controller being configured to control said firsttransfer robot or said second transfer robot so as to switch a currentcleaning line to the selected cleaning line.
 20. The apparatus accordingto claim 17, wherein said cleaning section includes a temporary base onwhich the substrate is placed temporarily, and the apparatus furthercomprises a controller configured to control said first transfer robotsuch that said first transfer robot transports the substrate to saidtemporary base and further transports the substrate from said temporarybase to one of said plural secondary cleaning modules to thereby skipthe primary cleaning operation on the substrate in any one of saidplural primary cleaning modules.
 21. The apparatus according to claim17, wherein said cleaning section includes a temporary base on which thesubstrate is placed temporarily, and the apparatus further comprises acontroller configured to control said first transfer robot and saidsecond transfer robot such that said first transfer robot transports thesubstrate from one of said plural primary cleaning modules to saidtemporary base and said second transfer robot removes the substrate fromsaid temporary base to thereby skip the secondary cleaning operation onthe substrate in any one of said plural secondary cleaning modules.